Maybe he is licking the area.Do you have him in a e-collar?Peanut was red down there it was from licking. So the doctor put a e-collar on him it took about 5 days to clear up. Is there green discharge ? If you do take him back to the vet this visit should be free-ask before going in--.Hope he is feeling better soon.Thumper and Peanut are sending doggie kisses your way.