Consult a Neurologist/ Epileptologist with all his details including description of the seizure he had, any family history and all investigation reports like EEG / MRI brain. From your description it is not clear if he is off medications currently.
Next Steps
Consult a Neurologist/ Epileptologist
Health Tips
Some of the Epilepsies in childhood may go into remission after a certain age.
Also understand that even many of the patients with Epilepsy may be able to lead to a successful life.