I have been on Mirena for a little over a month now and have gain...

I have been on Mirena for a little over a month now and have gained about 10 pounds. I have never been this heavy and have been thinking that I have not really been eating any differently (yes, there is always room for improvement). My pants don't fit and I am bloated. I have also experienced breast tenderness. I just ran a marathon three weeks ago (yes 26.2 miles!) and in the same month I have gained these 10 pounds. I am thinking it has to be the Mirena. I am seriously thinking about getting this out tomorrow during my one-month check to see if it is in the right place. I am glad to know that I am not going crazy!