I have read that sometimes putting the chick in a glass, and putting the glass in the brooder with the other chicks could help by causing the chick to jump up and straighten and strengthen the legs. It is worth a try.
It doesn't sound like splayed leg, but you may look that up to see. There is information on making a brace for splayed leg on the internet. Is the chick able to walk and get to food easily? If the exercise in the glass doesn't work, or the brace doesn't work, I would advise culling the chick. I once worked with a chick with a splayed leg deformity. It would fight the brace. It hopped on one leg when it was small, but couldn't support it's weight on one leg as it got bigger. It was a traumatic experience for the chick and me. I'm sorry
