Incorrect prediction?

I had a bbt spike on 2-27, and a LOT of EWCM that day, as well as some cramping/twinges of pain (I never cramp, even with AF, so this is unusual for me).  Originally, Glow had predicted 2-27 as my ovulation day, which seemed to fit. If ovulation day is 2 days after the peak day, then it's now predicting today to be my ovulation day and pushed back my period day, but I've had little to no CM the last couple days... What caused the change?