It could be a lot of things, though I would think it's probably a simple clogged pore. If you shave down there, then it could be an ingrown hair. Just keep the area clean and if it's a recurring problem, go get it checked out. good luck.
i went to college for esthetics, which involves waxing and facials. it is pretty normal to get that kind of a thing down there. chances are like already sated its an ingrown if your shaving or waxing. if it is, use a rubbing alcohol on a q tip and just dab at it for a few days, it'll dry it out and expose the hair. though if its closer to your vag lips be careful cause using rubbing alcohol wont feel pleasent down there at all!! its also normal to get an pimple down there. try not to irritate it. wait till its ready to be poped before you do anything.