Have the iud but recently have backache, abdominal pain, sore breasts, missed period, headaches, heavy discharge and constipation, pregnant?

Check: If you're sexually active then no method of birth control is 100% effective. An otc pregnancy test will help to figure this out. If this is a brand new Mirena (levonorgestrel) then pregnancy would've been ruled out before placement. New Mirena (levonorgestrel) can cause some pregnancy-like symptoms but then the pregnancy test will be negative.