I have a one year old hen (Autumn) who just went through her first molt. She has been balding on her head for quite some time. I do have a rooster and figured that was possibly from him. However, her back now is just balding without growing any feathers back.. she is growing just brittle quills that break apart and are very dry without any feather material growing on them. This is not happening to anyone else in the flock. I have them on an extra protein diet right now since the rest of them are just finishing up molting. Furthermore, I recently treated the entire flock for foot mites. This same hen, Autumn was the only one who looked like she was affected by these, but I treated them all nonetheless with Ivermectin. Her feet look much better since the treatment. I also performed a deep clean on the coop and sanitized every corner. I haven't seen any sign of the mites returning, though she is still shedding her old scales so her feet aren't perfect yet. Autumn has always been the "runt" of the flock, never got to full size for her breed (Buff Orpington), and lays smallish eggs. But she is active and acts normal and very spunky. I'm at a loss for what is going on here, I hope it's fixable and not just that her DNA is not so good. It's getting cold now and the poor thing is walking around with a bare back. Any help on this matter is so greatly appreciated! I love all my chickens and want them all to be healthy and happy.