I am currently using the birth control method called mirena iud since January 7,2015 so almost 2 years, I have been having my period regularly since the iud was put into place. Before this my period was NEVER regular. For the past two months I have not had a period at all and today I passed a softball size blood clot with no other bleeding (except a very small amount when I wiped once) but I am in severe pain. I have passed blood clots before and I know a little bit of clotting is normal but this thing was huge! I don't know if I should be worried or am I overreacting?