We have a week old chick who started limping on one leg yesterday. I have separated him and put him (or her) in with one other chick who seems to be very gentle with him as the others were just running all over him and knocking him down. Does anyone know why he might be doing this or how I might help him? Here is a link to a short video. He gets around to food and water okay, but doesn't try to walk much otherwise.