Anyone else ever get a 3 day temp dip before ovulation?

Holly • 2 children...Both teens...endometriosis. ..hypothyroidism. ..general infertility. Second bout of ttc began 09/14
Still no +opk...temp dip cd 11 12 and now lowest EVER cd13? ??....anyone else have this and still ovulate?...usually I ovulate by cd10:-(...New this month...vitamin b6...vitamin c and prenatal vitamin