I m 38 years old. I m on the first day of my period, and I just passed a piece of tissue about three inches long and half an inch wide. It varies in color from pink, dark red, to black. On one end it appears to have white stringed fibers or vessels. It ranges in texture from smooth to wrinkled. Just before, I experienced bad cramps, and last night I had a stabbing pain in my breasts. I always pass very heavy clots during my periods, but nothing like this. Should I be worried?