What Causes Teeth To Clench Tightly When MRI Reports Are Normal?

hi
i am nilesh
recently in sleep in moring time my teeth got clenched tightly
i could sence it and knew something is wrong but i could not stop
after some sec or min (i dont know exactly) i found teeth back to normal position. during attack i felt like i will break my teeth
i had this attack three times in one year
but this time intensity was higher so i went to doctor (neutologist)
he told me to get EEG and MRI of brain
reports found ok
but he gave tegritol 200 and asked me to take ot for three years
is it right?
do i have epilepcy?
i am 29 yrs old
how can i marrywith this problem?
pl s help
i went to neurologist