it is not uncommon to have seizures reappear after many years of seizure control. it is somewhat unusual to have them return and have him "seizing constantly". your son should be seen by an epilepsy specialist first to make sure the new events are truly due to epilepsy. in addition blood levels mris etc can be done to be sure there is not a fixable explanation. if his seizures are truly back and no clear explanation is identified your son is not alone. it is very frustrating that even with all the ongoing research we do not have a good understanding as to why a person's epilepsy can change so significantly in its response to medicine.
my son was seizure free for 20 years but is now experiencing seizures again. why might this be happening?