TMI- anyone have same thing happen?

I have 24 day cycles and up until about 2 months ago I have been very regular.  Last month I spotted brown blood only when I wiped for a week before period.  This month I started what I assumed was my period 4 days early and it only lasted for one day.  It was fairly heavy, went through 2 tampons and next day used one, then nothing! I have had some twinges in the uterus area and constipation. Did a test, came back negative.  I was just wondering if anyone has gone through something like that also, since it has never happened to me before.