On your labia? Any genital cuts/sores/bumps should be looked at promptly for accurate diagnosis, i.e. within the first 24 hours of it's appearance.
If it stays longer than 3 weeks, it's good evidence against herpes, but it could be a genital wart.
Bottom Line: It could be anything from an std to a boil.
It could be a number of things. It can be a ingrown hair or gential warts. you should be seen if you are having sex.