It really does sound like an ingrown hair, I've gotten these a few times. Just don't shave for awhile and see what happens.
But hmmm ... the whole "That's disgusting, you're just a child" was a pretty inappropriate remark to make to someone seeking sexual advice. Especially because for one thing, I agree with GeekGirl 4 isn't a very large number if you're being safe, and it's just as disgusting to have 4 sexual partners as an adult as it is to have them as a 15 year old. Come on now this is a place for advice not direct insults.