Placental Scab or Should I be Worried?

I am 4 weeks postpartum tomorrow. 4 days ago I suddenly had red bleeding again and quite a lot of it. I also noticed a lot of rather large clots. Some people have told me this is the placental scab coming loose and the bleeding is normal, but should it be going on so heavily for so long? I've soaked through a few heavy menstrual pads through the night, and I am up every 3-4 hours for a feed. I went through 8 pads in one day. And the clots are huge. I spoke to my doc and was told to go to hospital if the bleeding doesn't stop, but I'm not in pain and I really don't want to go unless it is necessary. Is this normal?