Hello,
Thank you for consulting.
Severe pain during sexual penetration (coitus ) termed as Dyspareunia can be due to many factors. As you did not mention, I assume you did not have any previous history of similar pain and it started only 3 months back. This excludes any congenital abnormality of your genital tract.
One of the common cause of painful coitus particularly in young people for Dyspareunia is due to faulty technique of coitus.
Dyspareunia can occur just at the attempt of penetration (superficial), after penetration is complete (deep-seated). Sometime is deap-seated dyspareunia, the pain may persist for few hours after sex. Any acute inflammation of vulva, vagina or cervix either due to infection or lack of secretions (dry vagina) can result in pain during penetration. Similarly a bartholin gland cyst or abscess which is situated at the opening of vagina can be painful during sex. Deep-seated pain even after completion of coitus can be due to conditions like ovarian cysts, tender retroverted ovaries, abnormal uterine tissue in pelvic region (endometriosis) or pelvic inflammatory disease.
I suggest you to consult a gynaecologist with your sexual partner for examination and counselling. Treatment will be based on the cause of pain. Infections can be treated by antibiotic creams or tablets. Oral contraceptives can be useful in some conditions involving ovaries and endometriosis. After ruling out faulty technique and any physical conditions causing pain, focus should be on psychogenic issues like fear of pregnancy or frigidity which can cause be the sole cause of pain sometimes.
Hope this helps. Do get back with any further questions