I can't see anything in your pic - it's very dark and kind of shadowy. :(
Have you ever had any kind of sexual activity? Oral sex? Naked grinding? Penetration? If you haven't, then the bump can't be an STD. It could be dermatitis, a fungal infection, an oil gland, or about a dozen other things.
If you have had sexual contact, maybe it's a wart of molluscum contagiagiosum.
Does it seem to be under the skin or on the skin?
In any case, you should let a doctor check it out to make sure it isn't anything that needs treatment since it's new for you.