I would go and buy a home pregnancy kit and do the test. I miscarried twice, and with one I knew I was pregnant and had bleeding for a week, and my home pregnancy kits kept saying I was positive. I ended up having the blood test done, and my hcg levels were going down, so that's when the dr. confirmed miscarriage. At least if your test comes back positive, you will know what is going on without having to go to the doctor. But if you're experiencing that much bleeding for much longer, I would definitely go get checked out - you don't want to have too much blood loss and pass out! My periods got heavier after my kids, and unfortunately the doctor says that's normal.
Take care and let us know what happens. You're in my prayers!