Could this be a miscarriage?

My last period ended 10/14. I started cramping heavily 11/28 and 11/29 I went to the restroom and this came out of my body. I’ve never experienced anything similar so I’m a little taken aback. 11/28 my bleeding was dark and sparse but I attributed it to starting my birth control again after a 3 month break as soon as my last period ended. Any help would be appreciated.