5 week old silkie / sebright cross with leg dragging and hopping on other.

[Cluckywucky]

Hi there I have a little 5 week old chick who has suddenly starting hopping around on one leg whilst dragging the other. On investigation there seems nothing else wrong, and it didn't seem broken. She holds it like a fist with the toes all curled up in both directions. She didn't seem to be in pain. I have locked the 4 of them together in a small run as they have for the last few days been running around free range in our large garden with the other hens which includes their mother. Any help and advice please would be most helpful.