Bleeding all day..

I am 5 weeks 3 days, and I started bleeding in the middle of the night and it's still going on. It resembles the first day of my period, started light, slightly brownish, now heavier and bright red. This is a miscarriage correct? I had to go all day at work smiling and acting like nothing is going on, as soon as I got into the car I started sobbing. I know this isn't normal