DITTO! Just check and see if it's not something wrapped around it's leg. If it's a injury, probably another chick stepped on it and it will recover in a few days.
Put some paper towels down and sprinkle the crushed up feed all over it, that way where ever they peck they find food, also put a shallow saucer with feed on it, that way they will catch on pretty quickly where the feeder is too!
that's pretty low for a starter feed, most starter feeds are 20 to 22% protein....anyhow, if your just going to use it in this emergency, it will be ok to use for a couple of days, until you can get some gamebird feed of at least 24% protein.