Thank You. I Have Positional Upper Abdomina/lower Chest Pain While

Thank you. I have positional upper abdomina/lower chest pain while seated. Eases upon standing. The more sitting I do the longer the pain lasts. Negative HIDA scan, negative stress test. Negative abd/pelvic ultrasound. Only finding with egd, colonoscopy is mild gastritis and hiatal hernia. I have had this pain for 3 years and the pain is progressively getting worse. It is controlling my life. I dread car rides. I sit sideways in a chair in the evenings.