I posted this before, but has anyone had this happen to them before?

I’m usually regular with my periods. But I’m 13 days late. Took a pregnancy test and it’s negative. Feeling nauseous, and small cramps on each side of my ovaries,

But randomly took a opk the other day and for two days it was high. I was bbt temping and the following day my temp shots up, and it’s been high for 3 days straight now. I’m wondering if I ovulated this month even though I hadn’t started my period this month. I never had this happen before. Any ideas what could be happening?