I used an Ovulator Predictor kit and ovulated on 4/26/17. 7 Days after ovulation light cramping. Possible implantation?

Implantation. Implantation can happen around this time depending when fertilization happened but the changes that happen are on a microscopic level so you wouldn't feel it. Take a pregnancy test a few days before your cycle and try to not stress. Make sure to take your prenatal vitamin.
Possibly . You generally cannot feel implantation, but if you had unprotected intercourse during that time it is certainly possible. If you miss your period, you should check a home pregnancy test. Good luck.