Ok? My Male Friend Has A Reoccurring Rash On His

Ok? My male friend has a reoccurring rash on his bottom. Sort of like a diaper rash but worse. It blisters and bleeds then dries and scabs. His skin looks really thin and shiny around the area when he does not have a breakout. I help him by keeping the hair in that area short, but he feels he gets it from wiping after a bowel movement and its only that. I think it is fungal and I'm searching for information.
Do you know what this might be? I see others have the same issue on the web