Ladies with IUD's..

I am sure this is the wrong message board to post this, however I cant find a more fitting one.

I have had my 2nd IUD for 3 years. I did not have a period for the 5 years I had my first one and have not had one for the past 3 years with this one! woohoo for me! :happy:
2 years ago I gained 90lbs, over the last year I have lost 63lbs. Last month out of no where I started my period, it lasted 3-4 days.
Last weekend I started cramping really bad but no period, then today...BAM....guess who graced me with their presense. Dang it :sad:
I am wondering if this is due to the weight loss. However last time I weigh this much (and less) I didnt have a period.

Wondering if any other women with IUD's have experienced this or ladies in general have noticed a change in their period after weight loss?