You need to go to the doctor for a proper evaluation. Boils on top of vagina is too vague to speculate.
start bathing with an antibacterial soap since boils are from bacteria that grows in areas that tend 2 be sweaty often
In some cases the boils could be caused by a condition called Hidradenitis Supprativa. Google it and see if it fits. Or it could be something easier to treat and that would include antibacterial soaps or soaps without scents, cotton underclothes, topical creams such as one called Steva. Hope this helps