Hello, It’s my first post on the forum so I hope i am at the right place. My hen, Buff (original name for a Buff Orpington, I know) worries me. She has a kind of hole in the feathers of her throat. She is healthy otherwise. I only have 3 chickens and she shares her room with a little Isa Brown. Buff is at the bottom of the pecking order. The hole is getting bigger. We treated the coop with Diatomaceous Earth. Any idea of what could cause this? Thank you so much for your help!