What have you found to be the best remedy for diaper rash?

DD got her first diaper rash (we noticed it Sunday early evening). We've been putting Boudreaux Butt Paste on it at every diaper change since then and now it's Wednesday afternoon and it doesn't seem to have gotten any better. It isn't getting worse, but no improvement either.

What have you found to work for you? Is it normal for it to take this long? It just looks so raw; I know it can't be comfortable for her.