I would give him some time to heal and let the medicine work and let the swelling subside. I have had birds with a bad scalp wound and/or eye wound that healed ok with minimal intervention. Sometimes the eye area is so swollen that the eye looks like it's gone, but a few days later once the swelling goes down the eye is there and the bird is able to see.
Usually this kind of wound only happens when there are too many roosters and not enough hiding spaces for the hens or lower ranking roosters to get away from the dominant one. If you have 4 birds, and know 3 are male including this one, I would bet all 4 are male. In my experience a rooster won't try to mount another rooster unless there are no hens available. I suggest adding more hiding spots to your enclosure with the other birds.
Usually this kind of wound only happens when there are too many roosters and not enough hiding spaces for the hens or lower ranking roosters to get away from the dominant one. If you have 4 birds, and know 3 are male including this one, I would bet all 4 are male. In my experience a rooster won't try to mount another rooster unless there are no hens available. I suggest adding more hiding spots to your enclosure with the other birds.