Thanks for your question on Healthcare Magic. I can understand your concern. You are having breathing difficulty on heavy exertion. This is commonly seen with heart diseases and lung diseases like bronchitis. For heart diseases you have already done ecg and stress test. So stress test report well tell about heart diseases. For Bronchitis, you should get done clinical examination of respiratory system and PFT (pulmonary function test). PFT will not only diagnose bronchitis but it will also tell you about severity of the disease and treatment is based on severity only. You may need inhaled bronchodilator (formoterol or salmeterol) and inhaled corticosteroids (ICS) (budesonide or fluticasone) on the basis of severity of the disease. Don t worry, you will be alright. First diagnose yourself and then start appropriate treatment. Hope I have solved your query. I will I will be happy to help you further. Wish you good health. Thanks.