Help!! What is going on?!

I posted a few days ago... My AF was due to arrive Wednesday. Wednesday morning I had light pink discharge, then nothing. Thursday night I had bright red spotting when I wiped then nothing until this morning when I wiped and am spotting brown... I've taken a couple pregnancy tests, all negative. I am so confused. This hasn't happened to me before.... has this happened to anyone else? Did your period end up showing up full force? Maybe I am sick or stressed. I had really bad nausea all week this past week to the point where I almost threw up & now I have pains in my lower back on the right side. I'm getting a bit concerned. Thanks for your help.