No advice medically, but my ladies wouldn't stop pecking at my leghorn cockerel's tail, to the point they broke some blood feathers. I tried reintroducing him several times over a month and they always went right for his tail, even after it was fully healed an no longer bleeding. Finally, I set him up w/ his own separate space in the coop so he is by them, can see them, but they can't hurt him. My hope is that his feathers will eventually grow back and they'll forget about it. I don't know about your coop/ run situation, but something like that may work for your little guy.