It sounds like she may have bullous emphysema, 'bullous' refers to 'bullae' which are basically big blisters on the surface of the lung, these can burst causing a collapsed lung due to air or fluid leaking from the lung.
I know a fair bit about the condition because I also have it, I have suffered two major pneumothorax, one was a complete collapse. I had surgery called a bullectomy to remove the bullae and a pleurectomy to stick my lung to my chest wall to prevent further collapses.