I have a Banty hen don't know how old, maybe 4 lbs. She's very under weight and weak and can't stand up. It started 2 weeks with her not being able to stand on one leg so I put in a little pen by herself but in with other chickens and now she can't stand at all. Her poop has been green and runny. I thought maybe the rooster hurt her but don't know. No broken bones. She was eating scratch and water but yesterday it seemed like she hadn't been eating or drinking anything. I took her to the vet and they said she was extremely weak, dehydrated and under weight so they gave her a calcium shot and some glucose and told me to force feed her and water her if she didn't eat and to feed her layer crumbles. I have in my house to monitor her and she has been eating and drinking. I'm using pine shavings for bedding. The vet doesn't know what is wrong with her. Could she have gotten to cold? I was told chickens can handle the cold and haven't been turning the heat lamp on at night. Plus she didn't have the other chickens to snuggle up with.