I have 5 hens who have been together since birth and are 4 years old. This morning I noticed Tiny, kind of in the middle of the pecking order, being attacked by the top hen and one who's normally at the bottom. They were huddled around her and pecking her head. I broke them up and they scattered (they are free range most of the day). Several hours later I went to shoo them into their enclosure because it's raining, and I noticed Tiny all by herself in the bushes while the other four were in the run. While I was herding them into the enclosure, the two aggressors started attacking Tiny again. I broke them up and removed her. I put her in a wire crate in a covered area of the enclosure so she can be with the flock and out of the rain but they can't attack her again. What could be going on? I have never seen this behavior before. What should I do?