I have 4 chickens (these are the first chickens we've owned, and they are about 11 weeks old. One seems to be injured. She doesn't seem to be sick in that she is eating and drinking heartily, but she seems to be having trouble with her left leg (maybe both, but definitely the left). She loses her balance easily, and when she falls down, she has a hard time getting up. Once she is up, she seems to be able to use her legs to walk, even run a little, but her balance seems to be more forward than it should. When she is eating, she bends at the knees and sits on her haunches rather than standing up. At night she is sleeping alone in the nesting area while the other three chickens are huddled together outside on top of the nesting box area. During the day, they leave her alone, but if they run into her, it knocks her down. I'm wondering what I should do. Thank you for your advice!!.