4 days missed period... Weird symptoms...Then bleeding

Ladies, I was missing my period by 4 days. This has never happened before. I've felt sick (dizzy, nauseous, and had headaches) for those 4 days, which lead me to think I may be pregnant. I tested and the tests came back negative.

Today, I started spotting in the morning, and shortly after I "got my period", or so I think.

Has anyone experienced this before, where their period is very delayed but then comes?

I guess time will actually tell if this is a "period" and or something else, although I can't imagine what that "something else" would/could be.