Cramps CD13

Mi

My cycles are long, and mildly irregular lately, (usually VERY irregular 55-80 day cycles) resently 30-38 day cycles. I've been trying to track ovulation but not intensly as we aren't ttc yet. But yesterday I had Horrible cramps like I was about to get AF. My chart says I'm 2 days from entering my fertile week. Has anyone else ever experienced this or know what could be causing it? I'm not super worried, it's just taht I've never noticed it before.