It could be just a period which is lighter. Periods can come early its your body at the end of the day. Implantation bleeding is just a spot of blood/ spot of blood in discharge. It can last 1-3 days. It hasn't got a flow and not every women experiences it its rare. Take a pregnancy test .
you could be pregant if you've had unprotected sex. The bleed you experienced could have been implantation bleeding, i think you should take a test just to check. (try using an early test)can I get pregnant 5 days before my period is due and then still ha