TMI TMI TMI TMI Implantation or WHAT!??? HELP!

So I’m on my second round of letrozole TTC with PCOS. My ob told me and my husband to have sex every other day, days 10-20... we’ve been on a good path with that... even exceeding it by a day lol. So anyways, last night we had sex doggy style. Nothing was ruff or hard. Our intercourse was more like me grinding on him if that makes sense. So, as soon as we got finished having sex, I started cramping...HORRIBLY. To the point I felt like I couldn’t move. I only felt it in my naval area/region. I’ve never felt this before but I’ve also never been pregnant. So moving forward, the pain lessened and lessened but all day today, I’ve been having a light flashback of pain from the one last night. I’ve been drinking straight water for he past few weeks and no sodas... I’m not irritated down there. No stds or history of anything other than PCOS. Has this ever happened to anyone!!??? The pains felt like severe cramping... help my glow sisters!!!!