My Rhode island red/white has white feather tips on her head. I was finally able to grab her and I tried to scrape the feathers with finger and some of them fell out. She also is pale in face. I'm thinking mites but nothing on her butt or under wings. The other two sisters don't show any signs. In Oct I had a pest possum or raccoon scare them badly. The one in question was scared the most and was caught in fence trying to get out. Any ideas?