My baby is shaking-need ideas!

I have a 21 month old son with a seizure disorder that is awaiting further investigation by a neurologist in May. Until then, we wait and play the guessing game with meds and seizures. As any good detective, I am trying to put the pieces of the puzzle together. The latest piece is a little confusing. When my son is woken up from sleep, he sometimes begins shaking as if he had the violent chills and does not stop for up to a couple of hours. He is alert and verbally responsive, but it's hard for him to walk and hold things because of his violent "shivers." He has what we believe to be partial seizures where his bottom lip shivers like if he were cold, but he does it at inappropriate times-like in 100 degree heat. He displays this whole body shaking despite being in footie pjs, under down blankets, in a hot bath, under layers of clothing with the heater in the car blasting. He eventually stops and continues on, but this only seems to occur when he's been woken from sleep-usually morning, but sometime naps too. He doesn't do it every time though. Any thoughts on this and if it is related to his seizure disorder at all or is it perhaps related to sleep. We are also wondering about his sleep, since he's had his adnoids removed for apnea and continues to have irregular sleep issues. Ideas????