I got a "suspected diagnosis" of autonomic neuropathy earlier this year because these symptoms all showed up or became more pronounced at the same time. The usual battery of cardiac and digestive tests didn't come up with anything conclusive, so apparently, like with MS, it is a diagnosis made through exclusion.

I pulled the plug on further testing because the procedures that had been done by then proved to be hard on the body and were making things worse. Further tests would have involved more invasive stuff, so I quit while I was ahead .

Here's some of the symptoms and some of the stuff that the tests showed:

Delayed/slow gastric emptying & intestinal movement (Everything seemed to be OK on endoscopy/colonoscopy tissue -wise; and the colon/bowel is unaffected).

A previous barium follow through showed some stomach emptying delay, slow movement through most of the intestine; but also rapid movement in some parts; as well as intestinal distension near the colon.
Now some of these symptoms have apparently become more pronounced.

(At times - not consistent)
Poor digestion; unaltered food particles in stool (TMI?)
Delayed bladder emptying and bladder distention (>1 litre)
Heart rate dipping to below 40 while sleeping
Heart rate not increasing sufficiently upon exertion
Heart skips a few beats
Slow heart rate (usually < 60 when awake)
Low blood pressure and not rising sufficiently upon exertion (average is <100/55)
Poor gag reflex; aspirating food, fluids and saliva
Problems swallowing solids (esophagus not working properly so food doesn't go all the way down)
Little saliva/tear production; negative for Sjogrens
Low adrenal function; though kidneys unaffected and better than average

Autonomic neuropathy is most common in diabetics but can also be caused by MS affecting the Vagus nerve which supplies most of the abdominal/thoracic organs. Brain stem lesions could be a cause as well but you'd need to check with a neuro on that (IDK).

I know that this all sounds nasty but as with MS symptoms, these too can be accommodated for. I'm still learning how to do that in some ways, but day by day, am getting the hang of it .

Hope that you get some answers and some solutions as well.

With love, Erika