One of my chickens is limping. Not just that- she's become the runt of the flock, and the other day I saw her hanging by herself in the coop while the others were out foraging- which is weird. I looked at her legs and feet and the toes on the limping side foot are curled under a bit- not splayed like normal. There's no sign of injury or blood anywhere. I wondered if one of my kids might have hurt her, but I can't imagine how they would have. Do chickens sprain their legs? Has anyone else seen this type of thing?