Gallbladder pain is an ache to severe discomfort mid right below the rib cage.
I went to the ER several times because of it, but nothing was found on the ultrasound, until I had a full on attack.
I ended up having sludge, which is basically sand like. Sludge is to a gallstone as sand is to a rock.
Sludge can get deeper than stones due to it being so much smaller, and that's why it didn't show on the ultrasound.