What Could Flat Bumps On Vagina Suggest?

I'm 21 years old and I have been having sex with my boyfriend of two years but about 2 months ago I started to notice a white flat bump/matter the size of a pea, it has irregular shape, near the bottom of my vagina opening (located on the piece of skin that separates the vagina opening and the anus) Can you tell me what this is and if could be the result of an STD?