Hi dear and thanks for your query.
As you describe it may be a Bartholinitis (infection of Bartholinis gland).
This infection have no relation with being sexually active or not,but being sexually active increases risk for this infection to occur.
In fact diagnosis is made only by looking your vulva
from a gynecologist.
I you haven't opportunities to go to doctor use Sitz baths 3 to4 times per day and soak with sterile gauze the area that you feel pain.
If the pain become intense and the increase more it size you should go to doctor.
All the best