Hi, Pneumothorax can be caused by various reasons including rapture of lung bullae, trauma, iatrogenic, post infective, underlying diseased lung or connective tissue disorders. Sudden onset pain and breathlessness heralds pneumothorax. When you mention PE, in medical terminology it often refers to pulmonary embolism. (or do you want to refer to pleural effusion, which accompanies a pneumothorax, making it a hydropneumotorax) Since the nature of pain you have described, it fits into pulmonary embolism. Causes for pulmonary embolism include prolonged immobility, surgeries, accidents, OC pills, hyper homocystenemia, cardiac abnormalities (afibrillations). Pulmonar embolism has been mentioned as a cause of secondary pneumothorax in the literature. And pneumothorax can subsequently lead to collapse of the lung. Hope I have understood your question correctly. Regards.