Chest tightness, back pain, shortness of breath, left arm pain. ECG, chest x-ray, blood test, echocardiogram are normal. Just mild Mitral Valves Prolapse.?

Not necessarily. Have you had a echo stress test or adenosine stress test? CT of heart? CT scan of chest/lungs??? Are you currently in the hands of a cardiologist? Although your symptoms "may" be related to MVP, heart and lung disease must be fully investigated.