Sometimes this pain is normal. You can take any over the counter muscle relaxant like TAB CYCLOPAM OR TAB DROTIN.
If the problem still persists it could be an urinary tract infection or a pelvic inflammatory disease for which you will have to do some blood tests urine tests and an ultrasonography followed by a visit to your near by gynaecologist.
Next Steps
If u have missed your periods then please a urine pregnancy kit test.
Health Tips
Sometimes such pain goes away in a day or two by itself.
nothing to panic about.
Handle sex with more caution.
Intercourse followed by ample foreplay will reduce post coital pelvic pain.
Learn to direct your partner as per your convenience and body strength.