What is happening?!

So..... My usual cycle lengths are about 42 days. I am currently on day 50, I had a positive ovulation test on day 34, 36 & 40. I tested this morning & got a BFN. At lunch time, I had really bad period pains (I usually get mild cramps). I tested cervical mucus, just to see if AF was on her way but no sign of her! I'm fed up with this journey now!! 😢