Lucky you to have made it so far! Destin in the purple tube is my go-to. Apply a thick layer at every diaper change. That usually gets rid of a rash in 24 hours.
I have found that Triple Paste is the best stuff. It runs about $20 at Target but it works and is worth it. Naked time is always good. If you want you can add some baking soda to the bath but if it isn't a horrible rash you don't need to.