I have had epilepsy since I was a baby. I was put on medication and for the same reasons I am having right now my mother would slowly take me off the medications. My question is why does the medication affect me the way it does?

Effects of the medication:

constantly tired in and out of it. Sometimes incoherant. Very dizzy and light headed. My head spins. And I feel the need to lay down most of the time. Can you help me