Diaper Rash Ointment

My little Gracy is allergic to some ingredient in diaper rash ointment.  I have tried all kinds.  I have no idea which ingredient causes the reaction, but she breaks out badly.  Anyway, after months of this Gracyn's pediatrician had me try this  little mixture:  hydrocortisone cream, neosporin, and vaseline.  Works like a charm!