Period pains and light bleeding

Becky
So I'm not due on until the 24th, been having unprotected sex nearly every day from the last day of my last period and all through my fertile window.
Now I've got brownish, red blood. Put a pad on and there's like 2-3 spots of blood on it and I get a bit when I wipe, only started this morning. 
Been having period type cramps too, could this be sporting/implantation?