HELP diaper rash!!

Okay, my daughter has pretty bad diaper rash (it looks red and blistery).. Her doctor is an hour away so I called them and they said to use equal parts of Desitin, Aquaphor, and Maalox on her bottom. But no stores around me carry Maalox! What can I do to help her poor little bottom?! Or what can I substitute for the Maalox? Just using Desitin isn't enough! =(