I have this recurring cyst-like bump that appears on my labia majora every so often. It and been re appearing for years mostly when my cycle comes and I wear pads that causes it to be kind of tight or snug in that area. It tends to flare up when it is irritated in that way. Or if I shave I would notice it slowly starts to become irritated and starts to swell and some rare occasions it swell to the point where it is extremely painful and I can barely walk or even wear underwear. I do not know if the tissue in that area is just infected. What is causing this and what can I do to prevent this from coming back?