Last night during exercise I began feeling cramps, as if I was getting ready to start my period. When I went to the bathroom, I felt something slip out. When I examined it, it looked like a small sac with strings of blood in it. It was surrounded by clear and white mucus like substance. I just had my period almost 2 weeks ago; it was normal. And I just had an appt today, where my culture came back negative for any infections. My doctor didn't have much to say to explain other than saying sometimes large clots get released and come out. This has never happened before and I dont find it normal at all, considering no one seems to have the same symptoms as me.