It could be an infected ingrown hair. It could be a blister. Try to treat it like such like making sure it's clean and cared for. If you feel like it is getting worse talk to a doctor. Also if you are getting waxes make sure it's a sanitary and reputable place, don't go anywhere unclean or raunchy. Vaginal area is very delicate and it's important to make sure you take care of it and that you are going to a clean place to do so. Also I recommend using a and ingrown hair serum or something that helps with ingrown hair prevention after you get waxed.