Cramps

I have been having cramps for the past two days in lower abdomen, they feel like menstrual cramps, according to Glow I'm in my fertile window but I have no signs that I'm ovulating. My period is irregular but this month according to glow AF is supposed to show on the 22nd. My last period was frm September 11-14. I BD'd about 4x 2 weeks ago...can this be a sign of implantation?