Is this ovulation cramps or?

depending on your cycle length.. if it is a typical 28 to 30 day cycle, CD 16 could be ovulation cramps.. don't think implantation cramp can occur that early in the cycle.. but best is to track your cycle with OPK to see when you most likely ovulate so that you can time your activity for best chances! All the best!!

Could even be premenstrual cramps