My cousin had the mirena, and let me tell you she had problems from day one pain, discharge, and just not feeling right. She had to get hers removed, I would just keep an eye on it and make a journal of your sythomes. You might have to get it removed, I hope you feel better and keep us posted.
I've had several mirenas and I prefer it over all other things I've tried. Every once in a while I get a random pain in the abdomen but since it only happens very sporadic then I just take a naproxen or ibuprofen and ignore it. I haven't had any problems that would make me want to get it removed. And I'm on my 4th one now.