I just came home after being gone for a week. One of my Plymouth Rocks, 8 months, has broken feathers all around her neck and no feathers on her face. Her skin looks pale and yellow in the sunlight. I don't see any broken skin. She is staying away from the other hens. I have not known her to be on the bottom of the pecking order so this seems unusual. Any thoughts on what could be wrong? I have 14 hens and one roo. Everyone else seems fine.