I'm hoping someone could take a look at these pics and let me know what they think is going on. I have silkie chicks and today I noticed one of them was missing a lot of butt feathers. When I got a good luck, I saw a bald spot right on the end of the butt, broken and missing feathers, and dirt. The vent itself looked fine, and the poop looks normal. It doesn't seem to have any other symptoms and I haven't seen the other chicks peck at it.
I soaked its bottom in warm water and gently cleaned it. I sprayed on a little poultry protector on the vent and under the wings, and I examined all the chicks for lice or mites and didn't see any. The other three chicks have normal fluffy butts.
(The grey one on the right - it looks a bit rumpless)