Search website: www.cerebralpalsysource.com - you can contact and be specific with questions you have. hope this is helpful.
I know botox has been recently used as a muscle relaxer for medical reasons. Although the needle is very tiny, it could of hit a nerve. It might be temporary. You need to see nachiket's doctor to do a nerve test on him. I will try to research info from my own physician, basic info, of what the possibilities are? Again, its just advice but you definitely need to go to his doctor for definite answers.
Good Luck to your son.