I just had same issue. The fly eggs were on it with in a day and I knocked him out yesterday. Tiny Maggots were just getting started. I cut it off. No blood in my case.
I used a spray called Catron that kills Maggots, then I sprayed it with Blu Kote. Then I smeared a cream called "SWAT" all over it and sprayed his body and antlers with fly spray that is water proof and says it lasts 17 days. Catron was obtained from a Vet and the Swat cream and fly spray at TSC. I also gave him Nuflor, Long Range and Multimin shots.
GOOD LUCK, Dont wait! The flies will get him !