What Causes Soreness On Outside Of Rib Cage While On Mirena?

I am a 39 yr old, 112 lb 5'5" women.I have had soreness on the outside of my lower ribcage in the front and abdominal bloating about 1" below my belly button and up to my ribcage. My abdomen is not tender necessarily but I know that it is there. I have no acid reflux or heartburn. I have used the Mirena for birth control for three years and rarely menstrate. What could be going on?