ovulation curiousity

I took the month off from clomid, and bbting. Out of stupidity, I ran out of opks. Since my cycles are pretty regular, I knew when to expect ovulation. I took my last opk on Friday and it was negative. Saturday had a lot of low back pain, and Sunday low abdominal cramping. Today, Monday, I was feverish and flushed all day and had annoying back cramping. I always have pms like symptoms around ovulation, but according to my symptoms, I was wondering which day you thought I may have ovulated? Opks help you predict 12 to 36 hours before, but which symptoms are most likely the "jackpot"? Thanks for you help