Burning pain in perineum
can be due to infection, trauma or inflammation .Kindly look for any vaginal discharge
or any eruptions. Meanwhile try do maintain a good perineum hygiene and you can use lubricant during sex. Medications which can help are topical anesthetics such as lidocaine
creams and topical estrogen cream.If there is no relief from pain ,you might need to consult a gynaecologist for local examination.
Hope it helps.