hello and welcome to healthcare magic.
since you have been on sodium valproate
since 1997 has your dose been adjusted? and are you consulting a neurologist?
because if you have been seizure
free since 1997 being on medications you should have been taken away from the drugs by gradually tapering the dosage after repeat eegs.
if not these symptoms could be due to side effect of these drugs i would advise you to get a blood levels of these drugs done and consult your neurologist.