His toes aren't curled anymore, since I had them in a splint for a few days. But he still can't walk. Is there a physical therapy or something I can do to help him walk again?
Time will tell if he can fully recover. You may be dealing with a disease like Marek's or possibly a genetic/developmental disorder.
I know you are doing everything you can for him.
You can try physical therapy on his legs, but it is sounding more like this could be permanent. Mareks disease can cause paralysis in one or both legs or wings, or the neck. If he had riboflavin deficiency with curled toe paralysis, if that is not treated promptly, it can be permanent. Some chicks are born with brain damage that keeps them from walking, We are all hoping that he show some signs of improvement soon.
He's taken the vitamins everyday since I got them. Marek's was the first thing I thought he has. I really hope that's not it. I love him so much and he doesn't want to give up either.