Why Were My Periods Light And Started Early This Month?

I normally start my period at the same time every month. Last month I started early and it only lasted 3 days. I normally have a very heavy flow and it was very light this past time and lasted a short period of time there weren't even any blood clots as usual. It was super light. Here I am two weeks later I've had a headache for a week and I just started cramping a little and this morning I go to the bathroom and I'm bleeding again.