Did you happen to save the clot? If so, you could take it to a medical lab and check it to be sure it was not placental tissue or anything like that. If you are on the patch, it is awfully unlikely you are pregnant, but it otherwise sounds like an early miscarriage. One thing you could do to test this idea is to ask your doctor to run a blood pregnancy test, if it had been a miscarriage, there might possibly still be a small amount of hCG in your blood. If no signs point to a pregnancy, then what might have happened is some blood seepage and then clotting, and then finally coming out. But I'd run it by your doc.
It does sound like an early miscarriage to me as well...Check Monday with your Doctor
and its o.k......