Silver Streak

There are two of them -- they're small, very fast and they look like streaks of silver when they zoom by. One of them has hurt his right front paw. I noticed that it was limp yesterday, and it seemed worse today. He can still climb trees and runs very fast, but I'm wondering if he broke it, maybe from a fall out of a tree. He didn't have an appetite today, only ate one peanut then climbed high up into the tree and disappeared.