Okay, so here's the situation: We have a small (16) flock of red broiler meat birds. They are just 4 weeks old 3 days ago. They are outside now and living in a coop w/ run, so nothing can take off with them being they're still small. One female is down and can't seem to get up on her own. We took her in as soon as we noticed last night when closing them up. She was a little bit in shock last night but now is not. She is eating and drinking just fine. I examined her and she looks perfectly fine in every way except her legs not working - the legs are not injured in any outwardly visible way. I read up on the forums last night and saw that it might be a slipped tendon so I looked and one leg does have a swollen knee joint. This morning all the other chicks are still healthy and active, so I don't think it's anything bacterial/parasidic/etc. This morning I took her out, changed her bedding, and re-examined her - since she wasn't in shock she responded to my prodding gently and I found that that swollen joint is painful to her if I try to extend it. The other doesn't seem to hurt her and she pulls it back up to her body if I extend it. I felt for a slipped tendon in both legs and either didn't feel anything or don't know what I'm looking for. I wrapped both her legs just in case it was a fracture or break that I couldn't see. There's no bumblefoot and no twisting that I can see. I also gave her poultry vitamins and crushed a tiny bit of B complex and put it in her water as well. Her poops are normal. Picture below! I am really at a loss - I've never seen anything like this! Any ideas?!