Period symptoms randomly changing?

I’ll make this as brief as possible. My periods have been super irregular since I got my IUD out almost two years ago. I’ll be consistent for 6 months and then won’t have one for three months, and then it’ll pick up where it left off.

But I have no idea when I ovulate. My last period was September 27th-October 2nd.

My entire life I’ve only had mild cramps a few days before I start.

For about three weeks, I’ve been EXHAUSTED and I’ve had the worst headache. Took a pregnancy test the day my period was due, BFN. Took another three days after I was late, also BFN. Figured I just wasn’t getting a period this month.

Yesterday, I had what looked like really really light spotting. Which is weird because I’ve literally never spotted before a period. Thought it may be implantation bleeding since I have no idea when I ovulated. But took a test this morning with FMU and BFN (I know if I just now implanted, I wouldn’t test positive. But my period was due on the 27th of this month so I’m very late at this point so it may not have been implantation bleeding.)Today, for the first time in my entire life, my nipples are just a tiny bit sore. Nothing major. But enough to notice when I was changing, and I was cramping for about an hour this morning in my left side only.

Has anyone had their PMS symptoms just changed randomly? Or could this be pregnancy that just isn’t showing up on an HPT? What should I even do at this point?