Perhaps you could make an appt to see your dr and have a blood test done for HCG to see if you are pregnant. If your not, then you can rule that out and investigate other causes.
I think its more than possible it can be implantation. I had cramps from 10DPO last cycle and got a BFP at 14DPO. That ended in early mc, but I have read that spotting and cramping are all signs.
Something else to think about is possible cyst from ovulation. I have also had that. Its when the egg releases quite violently from the ovary and fluid builds up in the follicle and turns in to a cyst. Symptoms include, late AF, cramping, dizziness, spotting and nausea. All symptoms of pregnancy.
Good luck
