What Causes Itchy And Painful Pus Filled Pimple On Vaginal Lip?

I have a small pimple like bump on the edge I my right vaginal lip( libia) it came to a little white head and pooped pretty much on it's own. A tiny bit of puss came out then very small amount of bood. It itched at first but quickly went to hurting as soon as it formed a white head. What is it? And there is only one bump not multiple. I also have a bv infection. Is that maybe what caused it?