I am so aggravated and confused!!! Please help!!

I am 3 days late which NEVER HAPPENS unless I’m pregnant, last month my “period” was not even a period it was spotting but I let it go because I figured it was a fluke...not only is my test negative but i have this severe sharp cramping pain on the inside of the left of my uterus I’m wondering if I’m developing a uterine infection from a previous miscarriage a couple months ago...I don’t feel well, I have the jitters like the shakes and my resting heart rate is faster, I’m dizzy, I have diarrhea, im developing insomnia over night and I’m having mental mood changes (out of the ordinary fluctuations) wth is going on here? I called my dr and have an appointment today I was jw if anyone else has gone through this and what was the cause? Could it be from the miscarriage?!