Hi I Started The Birth Control Pill Gildess Fe 1/20

Hi I started the birth control pill gildess fe 1/20 about 4 months ago, and for two weeks out of every month I will have light spotting and lots and lots of blood clots with cramps. I still had a slight period on the third week, until this month I didn't have a period, just lots of blood clots. I also have hypothyriodism but I am taking medication for that. I don't know if this is caused by my birth control because this did not happen to me with my prior pill, or if it could be my thyroid or another problem. Please help I am starting to get worried.