Cramping?!

I'm currently 7 dpo and since Tuesday, I've had mild cramping off and on. On Tuesday I got this very sharp pain in my lower abdomen and ever since then I have been intermittently cramping. Today the cramping got more intense (I noticed it more). The cramping has made it's way into my lower back now and it aches like it would if I stood for 12 hours straight. My period isn't due until next Thursday. Anyone experience this cramping before and it actually was implantation cramping?! I'm due for AF next Thursday.