I also have gone through the exact same thing. I had my third baby 2 years ago and 6 weeks later I had the Mirena placed. Prior to the insertion I was healthy. I'm a nurse and would sometimes work 16 hours with no problem. Soon after the mirena was placed I was exhausted and began having pain in all of my joints. I thought maybe it was because I had 3 kids and worked and was just exhausted. I cut my hours at work to just every other weekend and still felt exhausted and the pain began to intensify. I finally went to my PCP. Lots of tests were run with not much answers. I started prednisone and after a few follow ups and a few rounds of steroids I wasn't any better. She sent me to a rheumatologist and I was diagnosed with Rheumatoid Arthritis . I was started on a pill Plaquenil along with more prednisone with still no relied. Fast forward 2 years now I am taking injections to help control my RA and still am in severe pain and can not do half of what I did before.