I popped a pimple down there, but now it's back!
Your down there bump was probably just a pimple. It hurts because your pore is totally clogged, so releasing the pressure and all that gook is a good thing. But sometimes when you pop a zit, you don’t release all of the pus—that white stuff you squeezed out—and it can get even more clogged up, creating a bigger, more painful pimple.
Not to worry though, babe. It looks like this one is gone for good. If you’re fretting (or pimples down there become a constant issue), call up your doc and see if there’s anything else you can do to prevent them, aside from keepin’ clean. Exfoliating a few times a week with a loofah should help.