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
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.