Just use regular over the counter corn starch. It's a little messy, but it works like magic. My son-in-law calls it 'Magic Powder'.
I promise you this works! I've only been able to find this product at May's drugstores so far (I live in OK) and it's usually on the top shelf in the cream/ointment/first aid aisle in a small white jar w/royal blue lettering called Resinol (made by Mentholatum). It is a very thick calamine based ointment/cream and it stays put (for women, use a panty liner or use older cotton undergarments that you really don't care about anymore as it some does melt and might stain). It worked absolute miracles on my son's extreme diaper rash (he's now 11). I hope you feel better very soon!
Put a little vaseline mixed with Baby powder on the area will work wonders