I came home today to one of my barred rock hens half covered in blood. It was all down her breast, wing, and side. At first, I thought she was pecking herself, but after watching her, I think she was trying to get the blood off her feathers. I caught her and washed the blood off to see if I could find any wounds, but all I could find was bare skin under the wing and tons of feathers pulled out all down under the wing and across to the breast. I washed all the blood off, dried her off, and now have her inside in a dog crate to watch her. She seems to be eating and drinking fine. She's acting normally. I saw her poop, and it looks normal. What in the world could have happened? The other hens looked fine. Other info: I have 5 hens, all about the same age, have been laying for about 3 months now. They are in an enclosed run with access to a coop. I use hay for bedding. This hen seems to be the "queen of the flock" so to speak. She bosses everyone around, so it seemed weird that the others might attack her. I can't think of anything else. I didn't see any sign of a predator trying to get in. I did get two new hens a week ago yesterday. They are about the same age. They all adjusted well to each other. there wasn't any fighting. I had a rooster that I pulled out of the flock at the same time. But, I haven't seen any of the hens fight with each other or chase each other all week, so I figured everyone was fine. What should I do with her? I thought I'd keep her inside until she heals up. Should I put something on the bare skin or just leave it alone? Should I get antibiotics? What would rip feathers out like that? I'm afraid to put her back in the flock now because I've heard that once chickens start pecking each other and taste blood, that they turn cannibalistic. I'm a newbie, so feel free to educate me. This is a first for me. Thanks.