Hello Adrian, Chest pain/tightness can be caused by various reasons, including minor problem such as indigestion or stress, to serious medical emergencies such as a heart attack. And as mentioned in your post investigations like an Electrocardiogram or Stress Echocardiography are all normal, so any cardiac involvement can be ruled out. Other causes include: 1. Strained chest muscles due to overuse 2. Short-term, sudden anxiety with rapid breathing 3. Peptic ulcer disease 4. Pain from the digestive tract, such as esophageal reflux 5. Chest tightness is also noted as a side effect of intake of Lisinopril. Even in the causes involving the digestive tract, pain gets referred to back & shoulder due to irritation of diaphragm & phrenic nerve. So, it will be better to consult a Doctor & get a physical examination done to rule out other causes. So that proper management steps could be taken. Wishing you a Good Health. Let me know if I need to clarify further. Thanks & take care.