Post-partum bleeding with tubal ligation?

I had my daughter on feb 22nd, and I got my tubes tied during the c-section. I bled lightly for 4 days, then went a week and a half with no bleeding whatsoever. I started bleeding again, and for about 3 weeks it was heavy, like it should be. Then, I went to just spotting/light bleeding (one tampon or pad per day). I am still bleeding like this. I contacted my doctor at 9 weeks postpartum, and she put me on a birth control pill to control the bleeding as well as to ease my endometriosis. It's been 2 weeks since I started my pills, almost 3, and I am still bleeding the same. Today I started cramping so badly I have been on a heating pad for the last few hours, and I had to take 800 mg of Motrin. I don't know what to do, though I plan to call my doctor again on Monday. Has anyone else had this happen? How concerned should I be?