Hi Dr., I'm A 23 Year Old Boy And Has

Hi Dr.,
I'm a 23 year old boy and has been taking sodium valporate medicine since 6 years. Initially, three episodes occurred one after the other with a gap of 1 month each. I was on medication until my Dr. advised me to discontinue within 3 years. Within two months after stopping the medicines, seizure got triggered when I was playing football. Since then I'm on medication and not once the episode took place.
After reading through a handful of forums, I could understand that all the episodes happened when I was physically and mentally stressed. What I would like to know is that- what happens in the brain that eventually induces epileptic seizure in me?