If the vulva grows a hard bag, when pressed, the pain may be caused by the following reasons: first, the most common is the vestibular gland cyst, this time combined with infection, there will be painful symptoms, often found in the posterior joint left or right side of this mass, it is recommended to actively give anti-inflammatory treatment, the pain will be relieved. If you do not actively intervene, it may cause localized septicemia, which requires incision and drainage treatment. Second, it may be caused by a boil on the vulva. When there is acute inflammation on the vulva, and the inflammation is relatively limited, it will lead to the formation of a local boil, which will be red, swollen and painful to the touch, so you can keep the vulva clean and apply Bactrim locally for treatment, and if necessary, you can take oral antibiotics for treatment.