Here's the pine tar article I was talking about that might help you. Chickens feel pain, but will not show pain or hurt unless they are practically about to die - it's a defense mechanism since the other chickens will attack a wounded chicken and drive them out of the flock or eat them...
Pinless peepers on your hens might help. But that amount of damage seems extreme. If the pick-no-more lotion doesn't prevent all pecking of his head, you will need to separate him to heal. You can put an XXL dog crate in the run with your hens, and place him in it with his own food and water...