Welcome to the forum and your question is entirely appropriate.

The fact that you can yawn and experience momentary relief from symptoms would suggest that your sensation of dyspnea (shortness of breath) is neither related to any type of cardiac insufficiency or allergens.

Actual air hunger from cardiac insufficiency typically induces considerable respiratory effort by the patient and simple pulse oxymetry can indicate whether saturation is below normal. If it's alernatively from congestive heart failure, there are usually signs of pulmonary edema. Metabolic conditions can also cause dyspnea but other characteristic clinical signs are usually evident as well. None of these underlying conditions would best represent your symptoms as described. These patients also complain of muscular pain because the accessory muscles used to try and breathe deeply become fatigued.

The two most common and benign causes for patients to feel that they cannot get enough air are either GI related or due to anxiety disorder. For these patients, the initial sensation causes them to become concerned and begin trying to achieve an inspirational breath (the type of breath that achieves full tidal volume and has a pleasant and relaxing effect) but find that they are unable. They continue to focus on their respiration, repeatedly trying gain a deep breath and in failure to do so, will try to purposely initiate a yawn. During this time, however, the dysregulation can cause light-headedness and patients' fears become elevated that something is about to occur.

They often can't sit still during the event and typically pace about the room or fidget as they work to acheive an inspirational breath to promote comfort. Checking the pulse is not uncommon, as well as general vigilence to their body for other signs of a problem. The increasing fear can actually cause the diaphragm to tense up due to irregular and purposeful breathing patterns, which makes the lungs feel heavy and difficult to achieve normal respiratory responses.

Unwittingly, these patients have induced the sensation that they must actively breathe in order for respiration to continue and the awareness promotes fear.

The other common cause is GI distress, where bloating or indigestion causes upward pressure against the diaphragm and induces shallow breathing with the decreased ability to obtain an inspirational breath without forcefully yawning. Certain body positions, either seated or lying down, make matters worse. Once the GI symptoms abate, then breathing becomes less effortful. Similarly, patients in this instance also tend to become concerned that their sensation of dyspnea is related to some type of cardiac insufficiency.

So to sum up the response, I do not think this is related to your heart at all and you should try not to force yourself to breathe as much, simply allowing the body to respond normally. If you feel the compulsion to induce a yawn, then by all means do so, but less forceful efforts equates to the re-establishment of normal respiratory patterns.

Also be aware that a lack of quality sleep can easily induce the sensation that breathing is difficult or effortful and patients in this instance tend to sigh a lot more than normal. Any combination of the conditions described above can induce a feeling of shortness of breath in the absence of actual underlying pathology.

You'll be fine. Try and relax. Your tests do not reveal any type of cardiac problems and in the case of actual dsypnea, the cause would certainly be significant enough to light up the diagnostic panel and it's simply not the case.

Best regards and Good Health