Pain in your upper left abdomen has many possible causes, including:

Inflammation of your pancreas, called pancreatitis
Pancreatic cancer
Enlarged spleen, called splenomegaly
Inflammation of your stomach lining, called gastritis

Pain in this part of your abdomen can also start in your chest because of:

Heartburn
Angina, or chest pain caused by coronary artery disease
Chest pain not related to your heart
Heart attack
Inflammation of the tissue that surrounds your heart, called pericarditis
Pneumonia
Inflammation of the lining of your lungs, called pleurisy
Pulmonary embolism

Abdominal Pain on Right Side