What Causes A Lump On The Lip Of Vagina?

i have a pimple looking type of bump on the lip of my vagina and its always pussing and hasn t gone away its been a few months now and i am getting worried last year same thing happened but went away a few weeks later. but after i got my Papiloma shot so i thought that s what had happened, the same is happening again and its been a long time and no i have never had sex or touched anyone else s genitals or anything sexual like that so it can t be a sexual disease. what should i do????? and can i use neosporin