Feathers gone on back of RIR

[Smileycake]

My 5 week old RIR has lost her feathers on her back up to the stem part (I haven't looked at what the technical name is yet) and I don't know what the cause of it is or what I should do. I have 13 hens brooding in a rabbit cage right now. The RIR seems to act fine. I haven't seen any pecking of the other chickens and there isn't any bleeding on her back, just the feathers are gone. Does anyone know what this could be or how I can help it?

 

[Smileycake]

I just looked at my chickens and noticed that many of them had blood on their beaks. The one featherless RIR had blood near her tail feathers.
I separated her, now how do I take care of her featherless back and bloody tail feathers? How long should I separate her? Thanks!

 

[snowydiamonds]

As long as she is kept clean and you don't have to worry about flies, misquitoes, bugs, maggots, etc., she should heal on her own if provided clean housing, good food, rest and no pecking by other chickens, mine did recouperate fully as she came to me with a completely raw and bloody back. She's now one of the bossiest hens as I used to hold her every day, too.