Ovulation/implantation cramps for days?

Ok so we are on month 4 of TTC... Saturday the 23rd was my high chance day so let's just say I'm 3 DPO. I started cramping really bad right above my pelvic bone yesterday. Not to one side or the other but right in the middle. I started thinking maybe it's ovulation cramps but does that last more than a day? Same with implantation cramps, do they last more than a day?? I'm starting to get concerned that something may be wrong and that's why we aren't getting pregnant. Has anyone gone through this before?