You need soap, you need to scrub down there. It's no different than your arm pits or any other part of your body where skin hits skin. It's gonna smell because it's a natural harborage for bacteria. 3: If doing what I just described is physically painful it's entirely possible you have an un-diagnosed condition. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.