Hi Joan,
I'm sorry to hear your son is in so much pain. Your best bet would be to take him to a Migraine specialist. This doctor is an expert in Migraine disease and headache disorders devoting much of their practice to treating patients with these conditions. A neurologist may call himself a headache specialist, but it is really hard for them to be experts in any one area because they treat so many different conditions.
We have a list of patient recommended specialists you can see HERE.
Good luck
Nancy