I have never heard of reflex causing chronic gas and bloating in the intestines, constipation, dizziness, and palpitations. Is this very rare? I have GERD and am on treatment for it and I have no symptoms of GERD anymore, but still all the other symptoms and more that mandylynn0621 mentioned.
A lot of your symptoms are associated with acid reflux disease, except for the muscle weakness. It sounds like your digestive system is out of whack. Try these 3 things and see how you feel: Take a full spectrum digestive enzyme with each meal everyday. Drink a small glass of aloe vera juice before bed each night to neutralize acid. Aloe is a powerful healer of the entire digestive tract and will help with constipation. Take a couple of activated charcoal capsules whenever you feel gassy, bloated, or heartburn, but don't take with any medicines. This will soak up acid and gas like a sponge. All can be found at a health food store.
I know it sounds funny, but my husband had most of your symptoms for years, and he went around living undiagnosed, in fear for his life, test after test, nothing.... I don't know anything about the vagus nerve, but I do know that there are many nerves that are connected in your chest and back area that run from your sternum, and when you have digestive system problems, these nerves can send pain signals to remote locations that you wouldn't even associate with your stomach. And the "trouble breathing" part is also a symptom of acid reflux, which is why so many people with heartburn think they have heart trouble, when they really have a burned esophagus with radiating nerve pain.
Yes, I have had a colonsocopy.
This sounds almost exactly like what I have and I think the vagus nerve is associated with this. Have you had a colonoscopy for the constipation?