Use an ace bandage to hold the bird while you doctor him. Use an antibiotic ointment like Neosporin but NOT plus. I always like to give them some Poultry Drench straight as well as adding it to their water. I personally would but a bird down before taking it to a vet. You can soon pend enough in vet bills that you could buy a flock. If he doesn't start getting better then the humane thing is to put him down. If you are going to raise chickens you will have these type of things happen through no fault of yours. Take solace from the fact that you have done everything possible.