Two periods in one month??

katherine • Laughing is my fave
So I've always had a very regular period every 28 days. I've changed nothing in the past year. Same birth control. But one week after my last period was over at its normal time, I got another one for about 4 more days. Did I just have a very early miscarriage? And I know this is gross haha but can pooping make you miscarry?