For the past few days I have had a very strange thing happening, but it only happens when I am alone. I all of a sudden start shuddering in my lungs and rib cage, often extending to my shoulders and arms. I have no known health problems whatsoever. What could be the cause of these shudders? They last up to 10 seconds each time, and happen ranging from 2 to 20 minuets apart from each other, but only when I am alone. I live in Asia in a very very air polluted city, could it be my lungs are failing? When it happens my breath is very short and fast. But I am not in pain.