How To Know That The Idiopathic Epilepsy Is Completely Cured?

My son has been on epilim for four years after being diagnosed with ideopathic epilepsy at 14 yrs , and has now withdrawn from them over 4 weeks on doctor's orders. No seizures but when really tired he feels a slight twitch in his toes, and the feeling that his brain "clicks" like it did when all this began. He is scared that he is not 'resolved' so took two epilim out of fear? How do we know if he has not completely resolved the situation?