Since you can't make out the source of bleeding, surely we also can't make out the source of bleeding. It can be done by examination.
But your description shows that it could be injury. Injuries can be due to sexual intercourse or due to self stimulation. Your bleeding has stopped also.
If you are overdue by 8 days you should do urine
pregnancy test.
Next Steps
Please consult a Gynaecologist in your area. Tele-consultation will not be able to find the cause of bleeding.