Discomfort and pressure under right ribcage towards center at liver

This has been going on for over a month now. Some days its a little better and some days its worse. I dont really have any pain. Just an annoying discomfort below my right ribcage towards the center. It feels full and a good amount of pressure. Sometimes it gets worse after eating a lot.
I have had blood tests, an ultrasound, a CT scan but the doctors said everything came back fine.
It just wont go away. PLEASE i will take any advice!
My GI doctor wants me to do a colonoscopy but i dont think that is where the problem lies.