Hi, Welcome to HealthcareMagic Forum.
If you have had sex with a Stranger it could be STD
but since you have had sex during your Periods, the chances of Pelvic Inflammatory Disease
is higher even if you have had sex with a known Person. Your Symptoms also suggest Urinary Tract Infection
You may want to get yourself examined by a Gynecologist to rule out the exact cause and if possible get a Urine culture done so that the causative organism could be found out and antibiotics Prescribed against it. Drink Plenty of water.
Wish you Good Health, Take Care.