My son is 18 months old. He has red bumps on his bottom and lower back. The bumps are in patches. One patch on his penis, one patch on his lower back, and one patch right below the one on his lower back. I am using Nystatin cream, but I am not convinced it is a diaper rash. We battled diaper rashes up until he was 8 months old, as he has short bowel syndrome and his poops used to be very acidic to his skin. But haven't had one since then and his poops are much better. This rash does not look like what his rashes looked like in the past. Could it be chicken pox ? He hasn't been exposed to chicken pox that I know of.