Confused

Our 16 yr old son had his first possible seizure 5 months ago. We found him face down on the floor mubbling and disoriented and he had trouble breathing in his bedroom at 7am. He said only thing he remembered was the left side of face was numb and a loud noise in his ear and he passed out. He was sent to the hosptial they did ct scan and cleared him. 2 months later we actually witnessed what looked like a grand mal seizure " shaking in bed, foaming at mouth, eyes open and roll back in head, muscles tighten and than he tries to crawl off bed to floor and turn muscles turn to jello. It was around same time in the morning. We have been to a neurologist and cardiologist and have had a 24 hour test on the heart and brain/MRI/Eeg/Ekg/every blood test possible and everything is normal. We just did a 3 day nerologist video sleep study in the hospital and everything looked normal. After the 3 day hospitalized study the nerologist thinks it could be Neurocardiogenic syncope. We met with the other neurologist in the group practice and he says Epilepsy. We have him on low dose of keppra and while he sleeps he awakes sometimes and sits up and has a hard time breathing for few seconds. Everything happens before he goes to bed or on awakening. Any feedback would be great. Thank you.