What Is The Small Skin Bump On The Inner-side Of Vagina Lip?

I have a small skin bump on the inner-side of my vagina lip. It has been there as long as i can remember. I think i just started noticing it more because i masturbate alot more. What do you think? Can it just be because that is the way my vagina is? Also i just got checked for STDs. Sooo... what do you think?