What Causes Blood Clumps After Removing Mirena?

i had the mirena iud removed 5 days ago, due to pregnancy like symptoms(1 spotted less then a day period and 2 missed periods when i had regular periods on the mirena,nausea, sore breasts/leaking fluid, ). i had a pregnancy blood test come out negitive so i went into my doctor again to get it removed. They removed the iud and gave me a urine test to make sure i wasnt pregnant due to my syptoms before putting me on nuva ring.the test was negitave,so the sympoms were birth control related. recently i have been cramping thought it was a normal period intill i have had clumps that looked like skin covered blood sacks with my normal period discharge, it might just be clumped blood or something but i wanted to see if it was normal and if i should see a doctor.