<s>[INST] Which organ is located just under the left rib cage and toward the center of the abdomen? I have pain there that hurts mainly when I take a deep breath or have to sneeze. I don t believe it is my stomach. The pain comes nod goes....this time lasting for just over 3 days. [/INST] Hello! Welcome to Chat Doctor. On left upper side of abdomen is the spleen. Did you have any trauma to abdomen or chest? This can cause splenic injury, if trauma is on left upper part of abdomen. Also, this can cause pain on tip of left shoulder which is referred pain. Pain can also be musculoskeletal or due to increased secretion of acid in stomach. For correct diagnosis, clinical examination of abdomen by your doctor is necessary. In my clinic, after clinical examination, I advise ultrasound abdomen & pelvis, CBC. Treatment is done accordingly. Till then avoid hot/spicy food, alcohol, smoking, late night meals, reduce stress if any with yoga & meditation. Hope this helps. Wish you speedy recovery. Thanks. Regards. </s>