My Poland roo had the same thing happen, the poor guy. I don't think the feathers regrowing hurt, but the skin is probably still raw and tender from the attack. For my guy, I kept his bald spot coated in neosporin or Vaseline for about a week, until the skin was less red and inflamed. The skin is now light pink and healthy looking and he seems happy and comfortable. His new feathers are spiky and about an inch long. He doesn't mind me touching his head, so I think the growing is not painful.
But be careful-my guy got attacked and stripped bald twice. Some of the other chickens cannot resist pecking that baldspot. I keep him isolated in a large dog crate in the coop at night and closely supervise him during the day. If I am not in the yard, I drag the crate outside into a sunny spot and lock him safely up again. The Vaseline seems to disguise the bald spot, but I still don't trust the hens alone with him.
The day after Thanksgiving, I left the hens with him in the yard for 15 minutes while I made coffee and when I came back out, he was a bloody mess with his head and new feathers stripped again. I felt horrible and so guilty. He's looking a lot better now. I do not know how the hens will react towards him when he has fully regrown his crest and joins the flock again. I'm very nervous about it.
