I'm a new chicken mom to 3 - 24 week old hens. I've had them since they were about 8 weeks old. All has been well and they just started laying last week. Today I noticed my Australorp's feathers looked a little odd. When I checked, she has two sores on either side of her hind quarters under her wings (one side worse than the other) that have scabbed over. She is also missing a lot of feathers and her skin is red and irritated. I did observe that the other two were pecking at her and she kept trying to get away from them. I immediately isolated her and she is eating, drinking, and acting fine. We cleaned the area with peroxide and applied triple antibiotic ointment. No sign of mites or lice at all...everything looks clean around her vent. I have purchased Microcyn Poultry Care spray and "Pick No More" cover up lotion. Any ideas on what could have caused it? How long should I keep her isolated? I took the photo just after applying peroxide. It does not appear to be infected at all. Thanks for any advice to calm my nerves!! I feel like a terrible chicken momma!