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.
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.