Really raw diaper rashes, hard poops

My baby suffers from really bad diaper rashes, so bad that his skin peels and it’s raw and painful. I did have him on specialty formula as he couldn’t drink my breast milk or other formulas because it upset his belly. Now that he’s been on milk, (13.5 m old), his poops are hard or sometimes like thick paste, and hes still suffering from bad diaper rashes. I’ve tried pampers, huggies, and Walmart brand diapers, I’ve tried 3 different diaper rash creams, I leave his diaper off him to dry it out, I make sure the area is clean and dry when we’re home. What else can I do?! Any other parents deal with similar thing? Can’t get into the doctor until March so I’m coming here to see if there’s something else I could be missing or something else we can try until we get to the doctor appt.. 🙏🏽