Hi there -
I also have a hen that is getting pecked on her head. Quite badly in fact. The whole top of her head is a scabby mess and her comb has scabs on it too. It started out that she had a lame foot and couldn't walk for a while. So I secluded her from the others in a dog kennel because she couldn't get to the food and water and the chickens were picking on her then. When her foot got better I put her back in with the other chickens. They started attacking her like she was a new chicken in the coop. (I guess they are pretty forgetful!) She would hide face-in behind the waterer all day so she wouldn't get pecked. Poor girl!! She used to be at the top of the pecking order and apparently is now at the bottom since her little vacation. I have noticed that its practically all of the hens AND the rooster picking on her. So I'm assuming it was a pecking order thing at first but now I think it's a combination of she is weakened and the seeing, tasting blood thing. But her head was so raw that I decided to pen off part of the coop with tall chicken wire so that they can see her, but she can eat, sleep and lay in normal fashion while she heals. I did this with the chicks I raised so when they were big enough to be with the other hens, they were already used to them being in the coop. I'm hoping this works for Dottie in the same fashion. Good luck to you and Liz. I hope you figure something out.