Shaking Breath when sighing?

Ok, you know how when you have a really good cry, for about five or ten minutes afterward, when you go to take a deep breath it's rather shaky? Well, I've been feeling that a lot lately when I go to sigh or yawn. I've had shortness of breath for a while, but I don't think it could be COPD or emphysema, because I'm only twenty-two years old. If anyone has any opinions, I'd be glad to hear them, unless you're going to tell me that I need to take prednisone. Also, I'm in Australia and I'm not a citizen, so I don't have any healthcare, so it would cost me an arm and a leg just to walk through the doors of a hospital.