Welcome to HCM.
It is due to infection after unprotected sex.Take proper local care.Use medicated soap to clean.avoid tight under garment.
Start proper local and oral antibiotic under guidance of your doctor.
Go for certain investigation like cbc,thyroid
study,usg abdomen and ovulation study and also semen analysis
of your boy friend.
Consult your gynecologist for further guidance and medical management.