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 is His slave and Messenger.
There is no doubt that this person was sinful when he asked you to leave the room. Likewise, you were mistaken when you agreed to leave the room, thus leaving your mother alone with him. Being a non-Mahram to her, he is not permitted to stay in seclusion with her.
A Muslim is obliged to be sure of those who claim to treat illnesses and disorders whether or not they use the Quran and the Sunnah; in other words, whether they use the Sharee'ah-approved Ruqyah (Quranic healing). This is because resorting to sorcerers, soothsayers and astrologers is prohibited under the Sharee'ah. In this regard, it was reported that the Prophet, sallallaahu ‘alayhi wa sallam , warned that whoever goes to a soothsayer or astrologer and believes him would have disbelieved in what was revealed to Muhammad, sallallaahu ‘alayhi wa sallam. [Ahmad and Al-Haakim]
Similarly, it was reported on the authority of some of the Prophet's wives that he, sallallaahu ‘alayhi wa sallam, warned anyone who sought the help of a soothsayer and asked him about something and then believed what he said that his prayer would not be accepted for forty days. [Muslim]
As long as you were reluctant to take your mother to that person, then we ask Allaah The Almighty to forgive you.
Perhaps the watery cyst which your mother has in her brain is the cause of the headache she suffers from. It could have nothing to do with magic. You can resort to doctors once more to attain certainty about her case. We ask Allaah to heal your mother and grant her wellness.
Allaah Knows best.