You didn't mention if you have been sexually active? If you have, you should have it looked at by a doctor. Maybe it's nothing, but better to be safe than sorry. Also, you can get pimples there. Typically the ones you get in that area resemble an ingrown hair. It's usually a single medium-large bump. Or it could be an ingrown hair. Even though you don't shave in that area.
I don't know about that but I really think u should tell your mom about it. Even if u guys don't get along. She'll help u through it and answer any question u have. Don't hesitate to ask her about it. Just tell her