This happened to one of mine. It was mites. I'd read on here from someone else to make a warm bath with vinegar and dawn dish soap. Put them in nice and slow, up to their neck and bath them. Keep them submerged for five minutes. Rinse them in another tub exactly the same way. They love it and it worked. I'm going to keep treating her once ever 5 days. After the first bath, I've already noticed new feathers coming out. And her little bottom isn't red, just pink. DE is a good "dust" to use and I've also heard of a pesticide called Sevin that you can get. I'm just happy that the bath idea is working for me! It kinda brings you closer! Lol!