It sounds like mild asthma or bronchitis (which everyone has but it doesn't always manafest) your brachia close up and get stuck in a vacuum, you have no nerves in your lungs but your body interprets the problem and lets you know with a stabbing pain when you take a deep breath, it feels like you can't breath past a certain point.
To fix it, go somewhere with fairly clean air, blow all the air out of your lungs (letting the last bit drift out) then with your hands on your head (this opens your lungs up) take a deep breath and refill your lungs, it might take a few attempts to fill them right up but when you're finished the pain will be gone
