Cyst or implanting?

Nikki
What does it feel like? My Af is late 4 days. This morning for about 20 min I had period like cramps focused right above the middle of my Pubic bone..when I walked it felt like my uterus was falling out and when I sat it felt like I was sitting on my uterus...could this be late implantation or cyst rupture? I have never had one. Idk if I even have a cyst! But wth was that! Has anyone experienced that as implantation?