How can dr tell if you have a vagus nerve problem. how do they dignose this ?

Heart rate problems.: Unlikely that a doctor would be just able to diagnose vagus nerve problems. Very uncommon diagnosis and hard to conclusively say vagus nerve it self has a problem. Most people just have a " vasovagal " response that is different from actually a vagus nerve problem. As with all medical neuro problems getting evaluated by a neurologist would be best.