What Could Mild Bleeding And Spotting, Dizziness And HPT Negative Mean?

I thought I was pregnant because when I got my period this month it lasted for 1 day of bleeding then stopped for a day and a half then lightly spotted for 2 days. My periods usually bleed for 2 days stop for 1 day then bleed for 1 more day. Ive been extremely moody and have been having period like cramps on and off now for 2 weeks as well as dizziness I took a pregnancy test 2 days ago but cMe out negative? Why am I feeling like this if I'm not pregnant