No, I'm not currently, or have ever been, sexually active
I would go to a gynecologist. It could possibaly be an infection. Have you ever douched or lost a tampon up there?
I agree with sparkeler. Go to the doctor.
any idea of what it could be?
It could be PID. I'm not sure though. PID can be caused by douching & if left untreated can cause infertility. I would go to a doctor. It's better safe than sorry. All the best.