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. We ask Allaah to exalt his mention as well as that of his family and all his companions.
You should have made sure whether the discharge you had was Mathy or Maniyy as this implies a religious ruling which is performing Ghusl (i.e. ritual bath) if it was Maniyy, and washing the part of the body or the part of the clothes that are touched by the Mathy, because Mathy is impure. [Mathy is a prostatic fluid, which is a white, thin, sticky discharge caused by small sexual stimulation, and Maniyy is a white liquid that comes out with strength when there is an ardent desire, and smells like palm trees or dough.]
Therefore it is dispraised to neglect and not be concerned with such matters as it leads to neglecting and missing religious obligations.
Now, in our view, the ruling which applies to you is that of a person who could not distinguish between the two discharges.
The scholars have different opinions on this issue. It might be that the most correct opinion is that the person is obliged to perform Ghusl and wash the parts of the clothes that are touched with the discharge, considering that it is Maniyy and Mathy; this is one of the two opinions of the Shaafi'ee school of jurisprudence, and it is the opinion favored by Imaam An-Nawawi as he said: ''The fourth opinion is that he is obliged to do what both Maniyy and Mathy require a person to do; this is the view chosen by Ash-Shiraazi, …it is also the opinion reported by Ar-Raafi'ee, and this is what appears to be the preponderant opinion.''
Furthermore, the Maaliki jurists stated that doubting whether or not one is in a state of sexual impurity is like he is in a state of sexual impurity. For instance, Ibn 'Arafah said: "Doubting about being in a state of sexual impurity or not is like being in a state of impurity.''
Moreover, Khaleel from the Maaliki school of jurisprudence said: "If one doubts whether the discharge he had was Maniyy or Mathy, he should perform Ghusl"
Therefore, you are obliged to perform Ghusl if you had not done so after having had that wet dream, and make up all the prayers which you prayed in that condition.
For more benefit on how to make up many missed prayers, please refer to Fatwa 84645, and Fatwa 91472 on when a woman is required to perform Ghusl, and Fatwa 88716 on making up for all the prayers that one had performed while in a state of sexual defilement, and finally Fatwa 91473 on how to distinguish between Maniyy and Mathy.
Allaah Knows best.