Hello, everybody. I am a 26 year old man in relatively good shape. I am skinny and fit. I exercise regularly and eat healthy.

Occasionally I will have an episode where I feel like I can't get a full satisfying breath. When one of these episodes comes on, it can last for hours, or even a couple of days.

When the first started happening, I was very scared, and I went to the emergency room. Over the years I've seen many doctors, and I've had numerous EKGs, an echocardiogram, a spirometry test among other pulmonary tests, bloodwork, and that thing that they place on your finger to test the oxygen level in your blood.

All of the tests came out normal, and the finger oxygen meter tool always reads 100% oxygen level.

Despite this, I still get the sensation that I can't get a full breath. At home when I feel like I can't get a full breath, I will blow with the same strength in a peak flow meter that I would when I'm feeling alright.

It's not hyperventilation, as it does not always resolve when I try to breathe slower. Whenever I read up on anxiety-related breathing issues, most of the time they speak of hyperventilation.

When these breathing problems occur I notice I do have excessive stomach acid/gas. I do not think that stomach acid is silently getting into my lungs, because to get to my lungs it would have to go through my throat and vocal cords. My voice is not horse and my throat is not irritated.

Given that my heart and lungs always check out alright, I'm thinking that there's only two possibilities here.

1. When I get indigestion, excessive gas makes my stomach/intestines expand, which crowds my lungs.
2. Anxiety causes my breathing muscles to get tense, giving me the sensation of restricted breathing, despite the fact that I'm getting plenty of air. The indigestion that follows is unrelated and is caused by anxiety.

My questions here are:
Does anybody else have any experience with this kind of thing?
Can anxiety cause shortness of breath through some means besides hyperventilation?