HI!
The vulva is covered with sweat and oil glands. Not to mention hair follicles, and other varieties of skin. Most likely you have a plugged duct in one of these types of glands.
If so, one of two things will probably happen. Either it will come to a head and rupture, OR it will go away on its own by gradually shrinking.
There is no need to worry unless it continues to get bigger, you get more of them, or the pain of inflammation worsens. Rarely we have to lance something like that to get it to go away, It doesn't sound like any type of STD. It is of course always best to have someone take a look "down there".
I hope this helps!
Dr B
thank you! i found this answer helpful...
DR,any time I'm actively involve in sex with my wife,I use to have some pimple like rushes on my shoulder, chest and face, but if I withdrew for two weeks or so they will disappear.What could be the couse