I had unprotected sex on 3rd November and had ipill within an hour. My period is due on 11th November. I had sex on 9th Nov and started bleeding during it seemed like menstrual bleeding however the bleeding stopped today. There was no pain accompanied during bleeding or after. There's no irritation during urination. Urine routine came normal.  I have only one partner and most of the times we use condoms during intercourse.What can be the probable cause? Should I be concerned about it? Do I have STI by any chance?