Need a magic diaper rash cure!

As

My 8 month old has only had a few rashes since he’s been born but usually it goes away within a couple days if I use a&d ointment with some corn starch. However here in the last week hes had a consistent rash. Ive tried all the diaper rash creams I can think of. Off brand creams, desitin, aquaphor, Bordeaux’s butt paste, a&d ointment and corn starch. He’s formula fed so my milk factory is closed cause someone had suggested putting a little breast milk on it. Hes teething (hasn’t cut a tooth yet) and I know diaper rashes can pop up when they are trying to get a tooth. He doesn’t seem bothered by it but if there’s anything I can try to clear it up I’m all ears! Thanks!!