How do you make a boil on your vagina go away before it gets bigger?

Sit n soak. If you have a bath tub at home sit an soak in warm bath for about 15-20 minutes. Best if done at least twice a day. Other option is applying a clean wet hot compress to the area. Reapply when it cools and repeat. Wear cotton underwear during the day and no underwear at night to bed.
Boil. Medications, usually oral or topical antibiotics, will help. Avoid squeezing it as it may cause further irritation. A warm tub bath will help ripen the boil.