Leg Twitching and seizures

My son is 11 and was diagnosed with a seizure disorder 5 years ago.  He started having seizures in his left leg only.  While waiting on an initial appt. with a neurologist he had a grand mal at night.  I got an appt. the next day and he started Trileptal. He was seizure free for 1 year.  After a year, he started having seizures in his left leg daily as many as 15/day as well as nocturnal seizures.  I changed doctors and they changed his meds. He had an EEG/MRI and eventually a PET scan that all indicated something in the right frontal lobe.  Surgery was considered but with better control we decided to wait.   He finally got some control after starting Vimpat.  His daytime seizures stopped but he continued to have nocturnal seizures about once every 4 months.  He has had better control until this summer.  Now he has had 4 seizures in the past 2 weeks.  All during sleep.  After a seizure, his leg jerks once but frequently.  I took him to the ER after a seizure 2 weeks ago and they hooked him up to an EEG machine.  His leg jerked approx. 30 times in 90 minutes. The jerks are not epileptic so the Dr. mentioned psychogenic seizures. Upon returning home, I was able to record about 20 seconds of a seizure that the doctor said was epileptic but he still thinks there may be some psychogenic seizures going on. He wants to refer him to a psychologist and sleep specialist. He had a seizure last night and his leg has jerked all day.  The longer he goes without having a seizure the less it happens.  Does anyone have any experience with anything like this?  It is very frustrating.  We are on the 7th medication and now discussing a VNS.