As you described your condition its bit difficult to give a clear diagnosis for which an examination is necessary. At present i can think of is that there is a abscess
that got collected in the anal vaginal septum or these both could be separate like a fissure/thrombosed hemorrhoid(piles) with infection of a gland near the labia. At present what i would suggest is to start taking antibiotics preferably amoxicillin
with pain medication after consulting a General practitioner. Stool softener
like ducolex is also helpful. If the pain doesn't subside or increases please consult a GP/Gen surgeon/ Gynaecologist. Hope you find my advise helpful. Feel free to ask any further questions.