Confused! Help!

Mackenzie

So 2 days ago I had like a dark brown mucus like I was gonna start my period and then had dark brown spotting but still haven’t started my period nor had any symptoms of my period and I normally start around the 15/16th of every month! But I’ve taken a pregnancy test and it came back negative! What should I do? I also just had a dr appointment on the 16th and they did a test and it was negative.