Hey, How did you get your thoracic outlet syndrome diagnosed? @jenniferhunter . My Physical therapist has told me the same thing but I'm going to a neurologist to get a proper diagnosis.

Let me preface by saying that I also have GERD, and during my barium swallow testing an elevated right hemidiaphgram was found where paralysis was ruled out during a sniff test. I'm seeing the neurologist to get the thoracic outlet (nerve) in my left arm, pec, shoulder etc diagnosed as well as do phrenic nerve testing.

I also experience exactly what the OP wrote and can't run either because it feels like i have something constricted down my esophagus which leaves me with an air hunger feeling and when I can not satisfy it creates massive anxiety. I also find myself feeling the need to take deep breaths to satisfy, and have my own conclusion that this may be related to the GERD / LPR especially, if you're speaking of allergies, and if you've done a trans nasal endoscopy and see inflammation in the larynx you can ascertain that its causing "airway reflux / inflammation" and the possiblity of a hiatial or diaphgramic hernia causing the "constriction" like feeling you're left with when experiencing the air hunger.

I also find myself belching ALOT and have noticed that a good way to align this with GERD is to see if you do worse off PPI's or betterr with them. I have seen high dose PPI help with the breathing and air hunger feeling but still haven't dared to run with all other tests coming out perfect. A hiatial hernia can cause a lot of issues as air hunger comes from diaphgramic breathing and if there is a hiatial hernia "getting in the way" this may be the root of your symptoms. I would not down regulate the GERD at all.