If it is a boil a fabulous OTC treatment is icthammol. It is a black tar-like substance that you pout on the boil and cover it with clean gauze. it will draw out the infection if there is some.
Honey, it could be an infected Bartholin's cyst!
They are relatively harmless but really painful and can swell up to the size of a lemon!
Does it look like that?
http://www.picturesdepot.com/medical/12497/bartholins+cyst.html
You can treat it at home with sitz baths when it is small but you should definitely have it checked. There are many ways an ob can treat it, don't worry.