I Have A Tightness Under My Right Ribs And It

I have a tightness under my right ribs and it goes around to the back. I had my gallbladder out around 4 months ago. I thought it might be related to that but is still there. Some days it is worse than others. It feels better when I don't wear a bra, but is still uncomfortable. I am 56 years old and the heaviest I have ever been. I weight about 160 and am 5 6. I have had stomach scopes and ultra sounds and have found nothing. Wondering if it might be a muscular problem, just feels so very tight. Any thoughts?