Hi ! However effective the contraceptive
device may be and however least the chance might be, there is always a possibility that you might get pregnant unknowingly by chance. The pregnancy
might have got miscarried partially and there are retained products of conception in the uterus
resulting in passage of such clots or bleeding.
The problem could also be due to a side effect of the contraceptive device you are using due to the effect of hormones.
To know which is true, you have to get reviewed by your gynaecologist, who may advise you for a urine preg-test, a serum HCG and an ultrasound
abdomen. If all these things are alright, then possibly it is time to rethink of the alternative ways of contraception
without any hormone preparation.
Wising you an early recovery.