Is this my period?

I’ve had horrible cramps and had mild diarrhea today and I don’t get my period within 8 days. I am on the pill and never missed one. Had sex several weeks ago with bf, it was protected and didn’t break and got my period the next day last month. Was wondering is this my period coming early for this month or implantation bleeding(I doubt)? Just asking cause this is the earliest I’ve ever see it try to come