Help needed

Hello everybody...we noticed our rooster was unhappy for few days, left the coop slowly after all the hens left, until he refused to go out and was staying inside. Feathers on his tail went limp and dragged down on the floor and he tried to peck his behind. Upon giving him a closer look we found a lump of maggots beneath feathers around his tail, we cleaned and disinfected it with alcohol and powder we have for disinfecting wounds on pigs, but I think he is too ill and he won't make it...it even seems new maggots are going out constantly. I feel guilty for him, but there was no blood or anything to indicate wound beneath his feathers, he just suddenly got ill. Probably it was small scratch that got infected because he moves around the pasture all the time. Is there any way to go help him, I thought about cauterising wound with heat , but I am afraid it will only make him worse.