My chickens are picking each other feathers under the tails. Most of them are bald and the skin is red form picking. I think they are all doing it to each other. One was getting picked on more. It got really cold here so I brought her into the basement.( ours is warm) Her feathers grew back,but now I went to put her back into the coop and they all are attacking her pretty badly. I had to put her back in the crate. What can I do now? I bought some blinders for them but haven't used them yet.