What Does A Painful Bump On The Vagina Indicate?

For about a year-and-a-half now I have been getting a painful bump on my vagina. It is always just one bump it hurts very much the first time I got it I went to my doctor and ask them to test it for herpes I was afraid that it was herpes they tested it and it came back negative for herpes but the thing is is it still keeps coming back. Is it possible that I have herpes and it was a false negative? Is it possible that it is something else and not herpes? What could it possibly be?