Following organs are situated below the left rib cage, which can be responsible for the pain;
2) Esophagus or food pipe
If you are not at the risk or heart disease, stomach diseases are the commonest cause responsible for the pain. These can be;
1) Gastroesophageal reflux disease (GERD)
2) Peptic ulcer disease
3) Hiatus hernia
Antacids like Maalox or Tums with acid blockers like Prilosec are beneficial in above mentioned disease. Occasionally gall bladder pain can cause left sided upper abdominal pain.
If you stressed, sedentary, smoker, diabetic, have high blood pressure / abnormal lipids, over-weight, an EKG would be prudent.
Please feel free for your follow up questions.