What to diagnose for "dyspnea relieved by excess yawning"?

Air hunger: You might be describing what has been termed air hunger or hyperventilation. If so, it is sometimes due to a relatively increased rate of breathing, resulting in excessive loss of carbon dioxide; this causes a shift of ones blood acidity toward the alkaline side. The brain senses this; the result is anxiety and further shortness of breath. The treatment is rebreathing into a paper bag.