Bleeding ?

I had been bleeding for over a month. I had light spotting that Got a little heavier and then back light sometime early this week around Tuesday. Well I went to the doctor and everything was fine. I started taking the pill to control my bleeding, I was literally feeling drained and exhausted. So I took the pill and the next day the bleeding stopped but then I started feeling sick, so nauseous that I couldn’t go to work or even leave the bathroom, this happened for two days. So I stopped taking the pill but I still felt sick. And I just started spotting again. The doctors are saying nothing is wrong. But I’ve never bled for this long. I know stories of women who bled during pregnancy and had periods, I have friends who are pregnant and still get periods but they had negative test until doing an ultrasound, so I’m not sure what should I do ?