Hi! I am brand new to owning chickens and already have a sick one. I was talked into taking in 4 young hens from a lady that has several grown chickens. These were new chicks at Easter and she claimed the other chickens were picking on them. This was a friend of a friend and I know very little about where they came from. They aren't laying eggs yet but I honestly don't know how long it will be until they do. They are solid white. We built a 10 x 10 coop. I let them out part of the day to roam and put them back in the coop at night. We live in Tennessee and the weather has been hot and humid. Anyway, I know nothing about what I am doing and am trying my best to learn. One of the hens started laying down a lot 3 days ago. I noticed that she was very clumsy when she walked and now she can hardly stand. When she flaps her wings she falls over on her chest like a nose dive. Her poop was runny brown but now it is bright red bloody and runny. Her tail feathers are stained with it because she can't stand well and is laying down. She actually looks like she is sitting on her butt with her legs sticking out. The other hens appear fine but I don't know if they all could be infected with whatever she has. I feed them a starter feed that the feed store recommended and they eat whatever they find when they are let out. Her comb and skin on her head is more red than the other hens too but I don't know if that is just her color. I've only had them a couple of weeks. What do I do?