chinchillas

I have a pair of chinchillas that are 4 years old. The female (Dove) has one or two litters a year. This litter of babies is 6wks old. I kept hearing one of the babies cry out last night. I got up to check and couldn't see anything wrong. This morning he was still crying and when I went to see, Dove was trying to hurt him. This has never happened. He doesn't appear to be sick, but his feet and ears were cold. The other 2 babies are beige, he is gray, but we've had mixed colors in her litters before. Does anybody have a clue? I've got him in the bib of my overalls warming him now. Guess he will be my "pocket pet".