What's happening?!

I had a period from the 31st to the 3rd of June. It was heavy for a day or two then very light. I had thought I could be pregnant before the period started. But once Aunt Flow came, I dismissed the idea. A few days after my period ended, I started feeling nauseas with everything I ate, wnd I've had no appetite. By the 8th  I felt all my period symptoms again. And it's still going strong. My periods are regular. Could I be starting again? A week after my period? Or could it be something else.