I haven't done it, but I am pretty sure there are some posts in the archive here about removing the necrotic tissue from a prolapsed phallus. That would be the way to go.
I don't think they pass anything through the phallus (penis). In fact, I think the semen may travel on the outside of it, if I recall...
Just being closer to females will stir up his hormones - that's why you want him away from the girls - and I suspect it was drakes that messed with him...
I agree with Miss Lydia. He may have been attacked by another drake or drakes. How many of each in your flock? Cleaning that area up is important - drakes can live through this, but infection is a concern - hygiene makes a huge difference.
I would keep him by himself in sick bay for a few...