I Am Concerned I May Be Having A Miscarriage. What I Should Do ?

I was taking birth control for two years so I would not have a period. I had maybe 2 periods a year if i were to miss a pill i would start and just let the period finish. In Aug of 2009 I started taking my pills normally again so i would have a period and things were goin fine. In oct when i had my period however i was in so much pain i went to the emergency room thinking something was seriously wrong. They told me stop taking my birth control asap. I have had 2 periods since then and the cramps have been what they told me to expect but the blood flow has been normal, slightly heavier then my old periods but i expected that. I usually have my periods at the beginning of the month so this month when i didn t start i figured it was just from my body trying to regulate itself again. Then i started having signs of early pregnancy i took two tests both came back negative. So i thought nothin of it. I am concered i may be having a miscarriage because today i have been awake for 4 hours and have changed my super tampon twice. bleeding completly through my first one.