Diaper rash

So I've pretty much tried every diaper cream there is and I wash my baby with oatmeal based wash and let her air out without a diaper everyday but yet she still has a diaper rash going on 3 weeks!! She doesn't seem to be bothered by it but I sure am! Anyone have experience getting rid of stubborn diaper rashes, please help! Oh and my former pediatrician didn't seem concerned by it but we are seeing a new doctor June 7th