Help docs! i'm trying to find out what causes a spontaneous pneumothorax?

Pneumothorax: The most common cause are rupture of blebs or bullae, lymphangioleiomyomatosis as in catamenial pneumothorax, with some predisposing factors such as severe exertion and air trapping as in asthma can all cause non traumatic or spontaneous pneumothoraces.

Bleb: The usual cause is a weakness on the surface of the lung called a bleb, or ballooning of the wall. This is a weak stop, which can rupture when subjected to sudden high pressure. Blebs are common, and are rarely symptomatic. Treatment can be conservative, aspiration, tube drainage, or surgery.