Hi ~ I'm so sorry your son has had to endure this. Children should never have to go thru this kind of trauma!
I'd suggest that you see another Neurologist, as I don't think this one has all his ducks in a row.

Find someone else -- perhaps a Neurologist who specializes in children. Or if there is a teaching hospital nearby, get him in there. Those hospitals are the best to go to -- if they can't find something, then I just don't know!
Please let us know what you find out, will you? In the meantime, you and your son are in my prayers. God bless and please take care! Hugs, Lee