You really need to get to a doctor, the emergency room even.. with that amount of clots, you are in peril of developing severe anemia or worse. Make sure you're drinking lots of water and get to the doctor asap.
p.s. I have no idea what it could be but what you're experiencing isn't normal or healthy.
I thought the same as you did, that its maybe cos u didnt have AF for a year, but I agree with the post above that you should see a dr ASAP, if u have to make an appointment maybe go to ER if you can. Do u know why u didnt have AF for a year? Let us know what the GP said
I agree with mrs canada on this one - what you are experiencing is not normal and your blood loss could lead to serious complications. Please see a doctor ASAP as its better to be safe than to be sorry.