The cardiologist did a full work up on my heart to include a nuclear stress test, CAT scan, and sonogram. But at the first visit, based on all of my symptoms (to include the breathing issues) he suspected an ulcer and told me to start taking the sucralfate immediately. He said that an ulcer in the "right" place will make it feel just like your heart is fluttering...

And yes, before I ended going to the cardiologist, I went to a gastrologist and scheduled an endoscopy and colonoscopy. I did explain my symptoms to the Dr., and he said "an ulcer can cause that"... then he got called out of the room and I didn't see him again... he didn't give me any medicine. I was scheduled for the procedures 6 weeks later. two days before, the procedure it got canceled due to lack of nurses due to covid. When I did finally get the endoscopy, I had been on the sucralfate for a month and was feeling great. The gastrologist did see a couple suspect spots and did biopsies and they came back fine...

So to your point, yes... My GI Dr. suspected, and even stated that my symptoms could be caused by an ulcer, but wasn't thorough enough to follow through with treatment. The nurse practitioner came in after he left and gave me the standard ulcer speech... "if you see dark tar like stool... get to the hospital immediately", but gave me nothing to treat it.

The main point that I want to communicate here is that I have experienced "air hunger"/false dyspnea, on-and-off for years.... at times it has been severe. I now suspect that I have had ulcers that came and went with the symptoms. This last bout was just worse than I had ever had before and luckily it landed me in a good cardiologist's office that was interested in looking at the whole picture.... and I am in no way saying that ulcers are causing your breathing problems... I just note that there are articles/discussions here on this mayo site that link false dyspnea (i.e. air hunger) with GI problems, and so far that seems to have been the case with me. Good Luck