Susan,

Have you ruled out an allergy to the disposable diapers/wipes or the laundry
soap or fabric softener if mom is using cloth diapers?? Has she tried exposing
baby's bottom to air for a while after a diaper change? Has she tried
squirting breast milk on the rash?

Just  off the top of my head

Cheryl L Tompkins CLC
Phoenix AZ USA