I Had My Period For 8 Days Which Isn't Normal

I had my period for 8 days which isn't normal for me but I kinda brushed it aside. On the fourth day that I should have been off I had started bleeding again it was a light pink on the fifth day I was only spotting now on what would be the sixth day I am not doing anything. I have been cramping the last three days though like I would if I was on my period. I took a pregnancy test when I noticed the bleeding three days ago it came back negative now I'm not really sure what to do.