I recently aquired 3 hens from the owner of our new house. They're pretty much wild and you can't get near them. I'v been working on gaining their trust(I'v only had them a week). Well I was out yesterday fixing a fence and I heard squacking. I thought maybe one of the dogs got out and were getting the chickens. I ran to where it was coming from and the RIR they left was attacking a smaller(the smallest) black chicken. I pulled them appart and took the black one away to examine it. It's head is bald and bloody. It seems it's been getting picked on for a while. I have her separated in a wire cage in the barn. Thing is is that I don't think it's fair to keep her locked up all the time and she'll probably get picked on again after she's healed. I don't have a separate place to keep her and I think she'd get lonely by her self, should I find her a new home or will she be fine with her own area? Also if the RIR attacks any other birds she's gone. I'm going down their today and am going to bring the black hen up and get her cleaned up. Any thought on what I could put on her to help the healing?
A pic of the poor bird

A pic of the poor bird