Bleeding diaper rash

My LO had to go to the emergency room for a belly button infection on 4 July, and was prescribed Clindamycin as an antibiotic. Unfortunately, this caused him to have diarrhea and subsequently diaper rash too. The doctors switched his medication to Bactrim, which is helping out his diarrhea, but the diaper rash has worsened, and now his skin is broken and is bleeding. We’ve tried everything recommended to us. Petroleum jelly, Desitin, A&D, Aquaphor, Eucerin, Bordeaux’s, Nystatin, and even Neosporin. We’ve left him out of diapers and aired him out for hours at a time. He just keeps getting worse and my husband and I keep feeling hopeless for our little guy. Does anyone have any other recommendations? I feel like we’re at the end of our rope.