I Started My Period Last Month (March) Don't Remember The

I started my period last month (March) don't remember the exact day, I put nuvaring in 5 days later. I took nuvaring out early a week or so later and started my period 2 days later(April 3rd) lasted about 5-6 days. Now I'm having lower stomach cramps like I would start my period, now is normally around the time I would have a period if I hadn't took nuvaring out early, but I already had a period. What could this be?