Implantation Bleeding?

Autumn

Could this be implantation? I'm 12/13 dpo today. Period is due Friday/Saturday. I have little bits of cramps. It's only happened once when I wiped. Would it be more? And could it also be why my tests have been negative? Could they be positive after it? When AF starts it's like WW3 going on in my stomach. This is nothing like that. And AF is like clockwork. Always starts on time. I also had a dip in BBT yesterday & today. It's been high other than that.