Your symptoms sound terrible, @Bowser! Is it possible for you to get a FIESTA MRI to look at your vagus nerve in the neck area to see if it’s kinked or being irritated by something? It could also be irritated further down which could also be looked at w/ the FIESTA scan. The cause of nerve problems can be very difficult to diagnose.
I’m very sorry the antibiotics didn’t help. Are you done with the full course? Has the gastroenterologist done any further investigation into the possible cause?
Here’s the link to @GrnyAny’s post about her vagus nerve journey. There may be something there that can help you. Successful Surgery for severe Vagus Nerve Compression - #8 by Jules