Poor baby.. I have had all types of birds and I have never seen anything like that. But, he may have something genetic that just showed up now Or disease .. Either way I would put him down. That looks painful. And he will eat even if he is not feeling well . Animals hide pain well

You might be able to call your vet and they can help you with him.
Just please watch the others... I always remember what Spock said.. " The needs of the many far out way the needs of the few or the one "
Sorry