I study in Britain and thanks to Allaah The Almighty, I am a religious Muslim. One and a half years after traveling to Britain I developed painful symptoms such as exhaustion, migraine and cramps. These symptoms have become increasingly serious over time.
I have exhausted all the possible means of medical treatment and check-ups without any improvement. I went to some scholars to perform Ruqyah for me and diagnose my case; whether it is a case of Jinn possession or not, but there has been no change in my condition.
Later, I went to another person to perform Ruqyah for me, but he gave me an amulet and asked me to wear it. He recited to me something that I could not understand because it was in Urdu, yet I recognized some Quranic verses during the recitation. After wearing this amulet, I recovered my health.
Five weeks later, I told my friend about the story of the amulet, but he said that wearing this amulet is prohibited and told me that it contained the names of some devils. He convinced me to open it, and we found a paper inside it. There were Quranic verses, some Satanic names and numbers written in it, so we burnt it immediately.
Once we burnt that paper, the symptoms regressed. A few days later, I watched a scholar on Iqra TV saying that amulets are prohibited and that Allaah The Almighty does not accept the prayer of anyone who goes to those who make them for forty days.
Should I repent because I went to that person?
How can I cure this disease that has embittered my whole life?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

Allaah The Almighty afflicts the servants whom He wills with the diseases that He wills, to expiate their sins or raise their ranks.

Nevertheless, Allaah The Almighty has commanded us to seek medical treatment. It was narrated that the Prophet, sallallaahu ‘alayhi wa sallam, commanded us to make use of medical treatment, for Allaah The Almighty does not create a disease without a remedy for it, with the exception of one disease, namely senility. [Abu Daawood, At-Tirmithi and Ibn Maajah]

The remedies are either physical or spiritual, such as performing Ruqyah by reciting some Quranic verses, Prophetic supplications and good words. 

The whole of the Quran is a cure and a mercy. Allaah The Almighty Says (what means): {And We send down of the Quran that which is healing and mercy for the believers}[Quran 17:82]

It was also narrated on the authority of ‘Awf ibn Maalik Al-’Ashja‘i that the Prophet, sallallaahu ‘alayhi wa sallam, approved the Ruqyahs that they used in the pre-Islamic era as long as they did not include any implication of polytheism. [Muslim]

Therefore, some scholars say that Ruqyah must be in Arabic to avoid using any words that contradict Islamic monotheism or contain the names of devils and so on, as mentioned in the question. 

Ruqyah is performed by reading the Quranic verses and Prophetic supplications and then blowing the breath over the body of the sick or enchanted person, or by writing the Quranic verses and Prophetic supplications on a piece of paper, then the paper is put in water and the afflicted person drinks the water.  However, wearing such things or hanging them is prohibited by Sharee‘ah (Islamic legislation). It was narrated that the Prophet, sallallaahu ‘alayhi wa sallam, stated that enchantment, amulets, and the magic done by a woman to induce her husband to love her, are kinds of polytheism. [Ahmad and Abu Daawood]

It was also narrated that the Prophet, sallallaahu ‘alayhi wa sallam, supplicated against those who hung amulets, saying: "May Allaah prevent him from achieving what he has hung it for."

Amulets which contain non-Arabic words or names of devils are prohibited, according to unanimous agreement of the scholars.   Even if an amulet includes only Quranic verses and supplications from the Sunnah (tradition), it is prohibited so as to eliminate the means that may lead to polytheism. 

Consequently, it is impermissible for you to wear the amulet again and you have to repent to Allaah The Almighty from the prohibited act of going to a soothsayer. The Prophet, sallallaahu ‘alayhi wa sallam, said that whoever goes to a soothsayer and then believes in what he says, is a disbeliever in what has been revealed to Muhammad, sallallaahu ‘alayhi wa sallam. [Ahmad and Al-Haakim]

It was also narrated that the Prophet, sallallaahu ‘alayhi wa sallam, warned whoever goes to a soothsayer to ask him about anything, that Allaah The Exalted would not accept his prayer for forty days. [Muslim]

The right treatment for ailments can be summarized as follows:

•       Seeking refuge with Allaah The Almighty and absolute belief that He is the only One Who has the power to cure you.

•       Reciting the Quran and Athkaar ceaselessly -- particularly in the morning and the evening, at bedtime, when leaving and entering the house, and before and after eating. Athkaar are like a shield that protects the Muslim from Satan and his soldiers as well as sorcerers and the evil eye.

•       Using Ruqyah repeatedly until Allaah The Almighty cures you from the ailment you are suffering from (How Ruqyah is performed is mentioned in Fatwa 88705).

Nevertheless, you should know that Ruqyah may not work for some reasons. For example, the one who performs Ruqyah may not really believe in the potential effect of Ruqyah or may commit some sins that prevent supplications from being answered, such as dealing in usury or earning money unlawfully. Ruqyah may not work if the house contains prohibited objects that prevent the angels from entering it, such as statues, pictures hanging on the walls, dogs, or unlawful means of entertainment such as songs and indecent movies. Therefore, avoid objects and actions that could hinder the effect of Ruqyah, supplicate to Allaah The Almighty in the last third of the night, and ask Him to cure you and have mercy upon you. Never forget the Quranic verse in which Allaah The Almighty Says (what means): {Indeed, with hardship [will be] ease.}[Quran 94:6]

Finally, we supplicate to Allaah The Almighty to cure you and bless you with health, and remind you to remain patient and seek His reward in sickness and health; since a Muslim must express gratitude to Allaah The Almighty in times of prosperity, and be patient in times of adversity.

At the same time, you have to seek a remedy. You should do your best to gain the perfect reward for enduring this affliction patiently. It was narrated on the authority of Anas that the Prophet, sallallaahu ‘alayhi wa sallam, said that whoever is satisfied with the decree of Allaah The Almighty will be rewarded for his satisfaction and whoever is discontented with the decree of Allaah The Almighty, will be punished for his discontent.  [At-Tirmithi and Ibn Maajah]

Hence, do not give up the reward for patience and purify your intention. Consequently, even if you lose some worldly pleasure, you will be rewarded in the Hereafter, Allaah willing. This reward is certainly better than any worldly pleasure as Allaah The Almighty Says (what means): {But what is with Allaah is better and more lasting for those who have believed and upon their Lord rely}[Quran 42:36]