What Can Cause Pain Under the Left Ribs?
Pain under the left rib cage can arise from any organ in the left upper abdomen or chest, spine, or the left ribs themselves. In otherwise healthy people, spleen irritation and gas built in the colon are main causes of pain under the lower left ribs. Pain can be also psychological, for example from neurotic heart, but physical causes have to be excluded first.
During or after running, walking or other physical activities, irritation of the spleen capsule can cause side pain under the lower left ribs. Pain usually goes away after some rest.