Welcome to the NeuroTalk Support Groups.
I just saw your post here and I'm sorry that the Children's Health forum isn't very busy at the moment.
I don't really know what to suggest, except to say that as far as I know a positive Babinski sign in a 7 year old would be concerning. Why that is only in one foot, I don't know.
I'd certainly be asking for further investigation if he was my son and knowing that it "can" be a sign of quite serious conditions.
If you have a good rapport with his Paediatrician, then I'd talk with her again about your concerns. Considering all that your son has going on for him, then it might be helpful to know more.
I'm not sure what you mean about your son's migraines waking him in the night. How often is he having migraines?
My son had migraines from around 5 years of age to around 11 or 12 (totally grown out of them now as an adult). He also had night terrors as a young child. He had a complicated medical history related to a GABHS infection (Sydenham's Chorea) and was later differentially diagnosed with other conditions including Aspergers and a tic disorder/TS.
Go with your gut feeling. If you feel you need to know more then you need to go back and ask.
p.s. I thought I'd leave the link to the NeuroTalk
Cerebral Palsy Forum
here as well, just in case you wanted to post over there.
It's also a quiet forum but you never know, someone might see your post and have some suggestions.