I saw your posts on FB, sorry for the problems and for the misinformation too. It is possible that he only broke a blood feather and the blood is encouraging the other birds to attack the bloody site. Fresh feathers are full of blood and when they get broken the remaining stub is like a straw that will bleed and not clot over. Be sure to pull the stub out to stop the bleeding, a pair of needle nose pliers helps. To keep other birds from pecking at that area spray some Blu-Kote over the bloody area. Putting harsh chemicals on a wound is not a good idea. If you need to treat for lice, and it sounds like you don't, use Ivermec pour-on for cattle and put 0.40 ml on the skin between the shoulders and a tiny drop behind the crest for face lice.