Implantation bleeding??

So I had sex on the last day of my period on the 14th of June. I know that you can’t get pregnant while on your period. How ever I’ve been having slight symptoms like backaches and light cramps. My nipples are also sore. Today while at work I went to the bathroom and when I wiped this showed up in the toilet paper. I never spot before my period and I’m not due til next Monday. Is this implantation bleeding or just spotting before period. The bleeding only last for about 2 hours.