We had one like this also. My roo took a dislike to her, then the other girls followed his example and by the time they were done they had all the meat gone behind her comb down to her skull. I think it really traumatized her as well, as she was dazed and shook up. But we put her in a cage by herself, cleaned it and used neosporin as well. It finally all healed up, took about a month, she was so happy when she finally got put back out, and the stupid rooster immediately jumped her again and opened it up. I never did figure out why he disliked her or how he even knew which one she was, as she is one of several black stars that I can't even tell apart except for the numbered leg bands I have on them.
So, we got her healed up again, and I moved her to another home where a beautiful rooster immediately fell for her and the guy I gave her too says she is the happiest sweetest girl he has, and his rooster still adores her.
My rooster on the other hand decided to start in on another black star shortly after this one was gone, so he was given to someone else to go to freezer camp. I am sure they enjoyed him.