Odd menstral flow with IUD all of a sudden...?

I think what you're experiencing is normal to a point. I've had my IUD since '08 and I will go months with no problems, then all of a sudden I will see the same thing you're going through: cramps, weird periods, moody, all that. I think you've been lucky you had such a long time without any problems! I think part of it has to do with the IUD moving. I'm smaller and sometimes have problems with it sitting slightly out of place. It usually fixes itself after a month or two. Have your strings been getting longer or shorter (if you can still feel them)? If it continues for more than a few months or gets a lot worse, you may want to bring up to your gynecologist. Hope I helped!