Implantation or AF?

Monika🎀
So according to glow I am 8 DPO and today I've been experiencing some like tightening and sharpish pains in my pelvic region. I have 7 days until AF is supposed to show up. Could this be implantation signs? I've never been pregnant so I am not quite sure if it's AF knocking or implantation. Any thoughts?