Re: pimple on vagina?
Now, I'm not sure this is the same thing, but I often get infected hair follicles down there. They look like pimples, and sometimes pop. Sometimes they get really big and sore. I've had them on the outside and inside (don't ask me how) lips. If they are really small, don't mess with them. Hopefully they will go away. Soaking in a warm bath may help. There is a lot of friction down there from walking, wiping and such. It isn't too surprising that the hair follicles get irritated, and then infected. Sometimes they might even cause ingrown hairs.
Anyway, this has been my experience. Maybe it isn't the same thing you are describing. Once I had one pop on its own. That was very painful. I think my voice went up two octaves. I had my gyno check it out, and he said it was an infected follicle and to leave it alone. It healed fine.
Hope this helps anyway.