As others have said, increase the protein in the foods. Try a few cans of sardiens until they stop! You have to open the can for them though. and I would use something besides the sharp cans to feed them. That should stop it pretty fast. As for the bald heads/sores, they are going to targeting those birds until it heals. or you could try the blue coat to help stop them. There's another dressing called No Peck as well. I dont follow youtube videos due to data so if that was the link ( I am not trying to step on toes). One thing I am reminded of from twocrows or kc (years back) is that, introducing new birds to the colony will cause a massive aggression as they see them as outsiders to the colony. So if you did that (added birds), there lies another problem. But all together, I bet there was originally an aggression between the males that caused the sores as spring breeding is approaching, and since the hens are trying to pair, they are focusing in on the sore and pecking at it. Just my thoughts.