Yeah its prolly just a ingrown hair! But I do know pple that are known to get cysts or absesses in that area... ALL 3 CAN BE PAINFUL! I wouldnt worry about it, but if its bothering you, go to the doc. and get it checked out! and as Kim1989 said IF HAVING SEX: GET TESTED JUST FOR YOUR SAFETY AND USE PROTECTION ALWAYS!
it might be a ingrown hair which if it is its painful but nothing to worry about. you could always go to the doctor just to make sure
if your having sex you should go get tested for stds just incase