I know this post is olde, but I too have been experiencing this. I've had Mirena since Nov 2016. so 6 months ago. I never had much in the way of PMS other than cramps, but since getting the IUD, I'm SUPER irritable and emotional the same week every month (sure sounds like PMS, right?). I also go through many more highs and lows throughout the month than I ever did before. I used the pill for nearly 20 years before changing to the IUD, so I'm sure the pill was handling some PMS for me, but come on! I also, just want to be sure this isn't a problem with the Mirena.
So, thanks for sharing so that I can understand my own issues better.