A couple of days ago I discovered that my two golden sex links and my best layers (of course) were attacked and picked on by the other birds. Their feathers on their rears were pulled out, and in one case, the chicken was brutally pecked. I separated them from the others and blue koted them. About 5 pm, they were still alive, though one was a bit sluggish. When I went to water all the birds and close up the coop, she had died. She had an egg she couldn't lay because they had damaged her so badly. The other one is still alive and has less damage, but her vent is swollen and there's white stuff oozing out. I'm understandably worried and angry because I don't think there was anything that set the others off on these two chickens. They've been together since chicks and nothing has changed. I had been feeding them more scraps because my feed went low and I needed to buy some, but they were never starved and I've done this before. Any thoughts why my chickens in this pen went after these two? I had 3 RIR (2 hens/ 1 rooster), 2 BR, 1 BSL and these two GSLs in this pen.