Hello ma am and welcome. So you did not bleed immediately after sexual intercourse but a few days/weeks after? So in my opinion, this could very well be your period or a hormonal imbalance that can be caused by various factors. Of course, due to the deviation from the normal period that you have a pregnancy test will have to be conducted and I would recommend the same using an early morning urine sample or by just visiting your doctor who would confirm/rule out pregnancy, and also look for the exact cause if at all pregnancy is ruled out. Hope this helps. Best wishes.