Mirena vs Skyla weight gain

Carole
So I've had the mirena for 3 years in April and next week I am getting Skyla due to ive been getting bad cramps every 3 weeks or so. and the doctor thinks the mirena is too big which could be causing it. 
Since mirena I've gained 20-25 pounds with no change in diet or exercise if anything more activity then before the mirena. 
Anyone have the same problem with mirena and go to Skyla and lose the weight??