K.N.
Read this article from my pediatrician's website---I think you will either find remedies or determine if a visit to the doctor is necessary.
http://stapleton.pediatricweb.com/web145/pedwebarticle1.asp
My oldest had a blistering, weeping rash prior to his first birthday. I didn't take him to the doctor but this is how I treated it---oatmeal baths every time he had a bowel movement, zinc oxide ointment (dries and treats) rather than other ointments (preventative), motrin, and running around diaperless---the diaperless part, if he can be confined in an easy to clean area all the better, but getting air to his bottom will help the most.
Best wishes.