Hey sorry to hear bout your rooster, but I'm dealing with the same thing with one of my hens.
I noticed her on friday, and she was COVERED, but has obvious wound.
I washed with warm water and bout 2 quarts of peroxide, and packed with neosporine the first night (friday), and picked some maggots out of and off of her. She handled it like a trooper, but had enough after bout 45 min. So I put her in cage in basement. Saturday morning when co-op opened I got a product called....SWAT made by Farnam it is a insect repellent for wounds, and it looks like it kills the larva to. Saturday morning I washed her again, used a saline solution (no more Peroxide after day one) used the SWAT onitment, then covered with Blue Kote. when I got home from work saturday, maggots were GONE. I know for a fact I didn't get them all, but she showed no signs at all of them. There were dead on the towel, but I couldn't find any on her.
I continue with the saline washes, and either SWAT, or neosporine depending on how she looks. She is willing to eat egg, yogurt, and little mash, but now I think drinking may be a problem. I have medicated her water, and she not really touching it.
Good luck, and God bless.
TNT