Spotting? Implantation? Help!

Nicole • Saved by Grace. Happily married.

Hey everyone,

I have been spotting (brown) for the last few days and I have never spotted before in my life and it's making me worried. I do not think I'm pregnant and I even took a pregnancy test and it came back negative. I'm not supposed to start my period for a couple more days but could this possibly be implantation spotting or something more serious? Should I go to the doctor? Thanks!