What Causes Heavy Bleeding With Cramps When On Implanon?

Hi, I recently had the implanon removed. A week before I was due to have it removed I started bleeding very heavily with cramps that were like nothing I've had before I also had big blood clots that sometimes resembled tissue. It has now been 2 weeks and I am still having all the same symptoms.is there any possibility that these could be symptoms of a miscarriage?