Implantation bleeding?

Good morning everyone, here's my situation. Last week, my girlfriend and I indulged in a little sexual intercourse (This was around 2 days after the end of her last period). During foreplay, while i manually stimulated her i accidentally brushed my hand against my penis which more than likely had been producing precum and went back to manually stimulating her with aforementioned hand , we continued on despite this setback (w/ a condom), and the next evening got the morning after pill. Now one week later she's experiencing bleeding which she says was heavier this morning but is slowly getting lighter. I'm concerned that this may be implantation bleeding, does anyone here think it is or have an explanation as to what else it might be?

Thanks a lot