Have you switched to men's underwear yet? If so, what kind do you wear? Your underwear might be keeping moisture and heat in, a great environment for bacteria to grow.
Bottom growth makes any kind of tight underwear rub you raw and can create a sore spot, which is a great place for opportunistic bacteria to enter your body.
If you're wearing briefs, you might want to consider wearing boxer briefs. And go up a size if possible.
If you wear a packer even when you're at home, you might want to stop.
I usually wear boxer shorts under my PJs around the house, and switch to boxer briefs when I go out. Also something to consider doing.
Also, when you go to the bathroom, only wipe from front to back, never back to front! Dani's suggestion of washing is also an excellent one.
Hope this helps. Good luck bro!
Ryuichi