About 10 days ago we had to bring a severely injured chicken in the house for medical attention and time to heal(her injury was not from another chicken).Tried to re-integrate her this afternoon while the hens were free ranging (we have 6 hens, no Roos) and one of the other hens immediately attacked her. We finally got them apart and then noticed another hen had a nasty pecking injury on her wing and the chicken who started the fight with the chicken we were re-integrating had some dried blood on her chest that clearly didn't belong to her. So 10 days ago we had 6 chickens that got along fine, now I have one chicken who clearly attacked another chicken and attacked the chicken we tried to re-integrate. The 5 chickens out in the coop were in their coop more than normal the past couple days due to severe weather, which might explain the pecking injury, but I don't know what to do. We put the chicken that's been in the house recovering back in the coop with three of the other chickens who have accepted her back without a problem, brought in the chicjen with the pecking injury to clean her up, and brought in the mean chicken (kept separately) since I can't leave her with the newly integrated chicken in the coop. Any suggestions?