My son has a persistant Diaper Rash... I started small and has over few days grew bigger and bigger.. it is now spreading down his the inside of his legs?... Extremely red but no broken skin... He itches at it.. We thought yeast infection I started using the nystatin we have and it doesnt seem to be helping.. We keep him as dry as possible... Is there anything else it could be?... Is it possible that he is all of a sudden allergic to the diapers?