When my daughter had a really bad diaper rash, her pediatrician told me to use whatever had the most zinc oxide, because that would keep the moisture off of her irritated bottom. That was Desitin at the store I went to.
In addition, he said to refrain from using wipes if possible, instead I used damp paper towels or damp toilet paper. The wipes have alcohol in them that irritate their poor, sore bottoms.
Another thing he suggested was to let her air dry as much as possible. I'm not sure how old your baby is, but mine was barely rolling over so I would lay her on a towel on the floor and let her air dry. She did, and still does, love to be naked so this wasn't a big problem for her. I know it's winter now, but if your house is reasonably warm it shouldn't be too big of a problem.
Also, Aveeno makes an oatmeal bath for diaper rash. I don't know if this helped her diaper rash or just made me feel like I was more pro-active, but I bought the off brand at walgreens and it didn't seem to hurt.