I have a dull constant uncomfortable feeling under my left rib cage feels tight yet a heavy sunken in feeling i feel as though my rib moves if i bend that way its hard to get comfortable in any position no injuries no pain w/ full stomach or breathin?

That area is a meeting place for lower anterior ribs &rib cage muscles &nerves,base of the left lung,spleen,left upper abdominal muscles,splenic flexure of the colon,edge of stomach&duodenum. Dull symptomatology there,in the absence of other symptoms or injury could be of minor musculoskeletal origin. Have an MD examine you. Any appropriate testing can be done depending upon the assessment.