S.L.
With my two boys, I didn't have any bleeding problems, but I bled up until right before my 6 week check up. The clots sound a bit scary, but I think I remember a little bit of that, too. I also remember that it would stop and start again, and the best way to get it to stop was to rest more. I was told that it's the way to gauge if you're doing too much. I was so tired of bleeding that I would rest just to get it to stop! I wouldn't be too worried, but trust your gut.
My friend who's has 5 babies also told me that she's almost canceled her 6 week check ups for all her babies because she hadn't stopped bleeding.