I was thinking infected hair folicle too, but you said it was the
Labia Minora (which you are right about), which is the
inner lips, so that ruled that out for me. Also you've had this for over a year, so if it was an infected folicle, it would definitely have gone away by now.
I would get this checked out very soon because this isn't something to diagnosis on here. At least "sexual endeavors" can be ruled out, lol I like your choice of words btw.