Exercise-triggered racing heart? Or, esophageal spasm?

I'm a 29-year-old male, 181cm/82kg, non-smoker. I have diagnosed reflux esophagitis (GERD), confirmed by endoscopy and esophageal pH monitoring. Symptoms have been going on for about a year and a half.
I get episodes of chest pain and burning, along with a racing heart — but only triggered by physical exertion (walking on flat ground is fine). Swimming reliably brings it on, and even lifting something moderately heavy sets it off. When I'm sitting or lying down, everything feels completely normal.
I also deal with bloating and burping, especially when I overeat.
I've had prior surgery for hyperhidrosis (sympathectomy), and also had a paralabral cyst removed from my left shoulder — not sure if either is relevant here.
I've been to the ER 4 times and seen 3 different cardiologists — EKG, echocardiogram, Holter monitor, and cardiac blood markers have always come back completely normal. I was told it's an extra-cardiac issue.
I've tried Nexium, Gastroprazol (pantoprazole), Famotidine, Gaviscon, and Exoss — none of them made a real difference.
I'm currently working with a nutritionist on a strict GERD-friendly diet.
Has anyone dealt with this kind of pattern — exertion-triggered chest pain with burping, heart fully cleared? Could the sympathectomy be connected to the exercise-triggered racing heart? Does this sound more like esophageal spasm rather than typical reflux? Is it worth pushing for esophageal manometry?