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Depending on how large and how painful the area is, at some point I think it will be better to go to emergency.
Most likely your painful swollen area is a Bartholin abscess. This occurs when the Bartholin gland (there is one on each side) gets plugged, and then becomes infected.
The treatment is heat, and at some point it usually needs to be drained, as it's filled with pus.
Heat can be from sitting in warm water or putting a hot washcloth on the area covered with a heating pad.
When it is hurting too much, then it's time to see a doctor, either in emergency or wherever. You'll get much relief once the area is opened and the pus allowed to drain.
Antibiotics are usually not helpful, as they can't reach inside the infection. Best wishes.