Eating In: Infant, Triple Paste

Seeking Advice on Chronic Diaper Rash

My son has been getting recurrent diaper rashes that are terrible! I have tried every diaper cream out there, Triple Paste, Desitin, A&D, Balmex, But Paste, Aveeno, Cortaid, and even Nystatin. I let him air out as often as I can and it seems to be the only thing to help until he goes again in his diaper - there the rash is again. It was so bad it bled. My doctor says there is nothing else I can do. HELP??