What Causes Heavy Bleeding After C Section Delivery?

I had a baby via c section 4 weeks ago, and only bled for 3 weeks, I took 2 morning after pills 1 Monday just gone and 1 the Saturday before that, I started bleeding very heavy yesterday and has continued to get worse to the extent I can feel it coning away as I walk, I have no other symptoms except slight period pain, is this normal?