Sore on male cats stomach

Question
My cat has a sore on his stomach. The best I can describe it is that it is black, it is leaking fluid, and it has a small tooth like mark in the middle of it. I can't afford to take him to the vet and that is why I am asking here.  

Answer
A black sore is bad. Leaking fluid and pus is also bad. Black means it's necrotic, in other words, rotten.

Like it or not he needs to see a vet. He needs the wound cleaned off under an anesthetic and then be given antibiotics for a week or so. Such is the cost of pet ownership.

You might want to get some pet insurance if he does this often. But it will just get worse instead of better if not taken care of.

Call the vet next week.