Is It Normal To Have Cramps Weeks After Being Fitted With Mirena Coil?

Hi, I had the Mirena coil fitted two weeks ago, but am still experiencing quite bad cramps. I have been taking painkillers every day, which can't be very good for me. Is this normal? Also, I have had a few bouts of cystitis, is that related? And although I managed to find the threads once, I'm now struggling to locate them. Is that normal? Thanks so much!