I would go to the hospital. Bleeding is not abnormal in some women, but the heaviness and the clots are signs of possible miscarriage. At least they can tell you if you're in active miscarriage...if they don't tell you, ask if your cervix is open or closed. If its closed, it means you're not actively miscarrying. This happened to me, though not heavy or with clots, and they said that when you bleed in pregnancy it means your chance of miscarriage is about 50/50.