I'm late.....

Kristen
So I am usually a very very heavy bleeder. However, 2 days ago I started to spot dark brown. I was supposed to start my period 2 days ago, but nothing has happened but the spotting. I have never spotted. Ever. Not sure what to think here. I took a pregnancy test tonight but it came out negative. Any suggestions. I'm 32 years old and have never spotted before.