What's up with my period??😭

I have been having light brown/pink discharge & I was supposed to start my period yesterday which I thought I did because I had light cramps and I had a gush of heavy blood come out (TMI SORRY) so I thought it was my period but after that nothing else came out?? Today there's no bleeding just brown discharge.. My period usually last 5 days and starts out heavy. I only bled for an hour? I'm convinced this bleeding is not my period. I'm confused.. I always have protected sex. What could this be??  Your comments & advice would really help! thanks.