Early AF (please respond)

Kendra
I started my period 5 days early today, & it is also heavy with a brown color to it. Does anyone know why this has happened or have also experienced this? I have never experienced this before. This was my first month ttc since my daughter was stillborn in August. I took a pregnancy test yesterday & the day before & they both came back negative so I don't think it was a chemical pregnancy or miscarriage but I could be wrong.