PERIOD WAS LATE AND THEN THIS CAME OUT

My period was expected on August 15th, that date passed and I waited for it to come. This morning I had sharp pains and cramping in my stomach and back. The bleeding started and continued on for the rest of the day. I went and took a shower and this was hanging out of me. It was painful to pass and bleeding has slowed down since I passed this. Anyone know what this could be?