Just asking....do you mean Xanax the tranquilizer, or Zantac, the acid blocker?
These two names often get mixed up by doctors and patients when orders are made orally over the phone, or discussions happen.

So I am assuming you mean Xanax, the benzodiazepine. Now this drug has some anticonvulsant activity. So that brings up the thought that your stomach/abdomen issues might be seizure related? Here is a Wiki on abdominal seizures:
http://en.wikipedia.org/wiki/Abdominal_epilepsy

These are not common, but diagnostically when anticonvulsants work on the symptoms, it is diagnosed that way.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1856820/

Using Xanax in the short run will give you some relief. But as time passes, you will quickly become tolerant to it. Most doctors will not give it therefore, for long periods of time.

It is possible that your symptoms have been conditioned in your brain, like chronic pain patients have. If you block those symptoms you may enable the pain loop forgetting it all. So it is worth a try to see what happens. When patients respond to Benzo drugs the doctors often diagnose them with psychiatric labels. Prepare for that. But it is possible that an anticonvulsant drug with less habituating traits might work for you too.

Xanax is a gaba receptor agonist. It works by enabling the inhibitory neurons, to work better. The nervous system has many inhibiting tracts, which keep us in balance from overstimulation.

Gabapentin, the drug often used in PN is not related to GABA, and works differently to modulate nerve transmission involving calcium ions.

So while this condition of abdominal seizures is rare, you might read up on it and discuss it with your doctor. It might be related to your previous medical history.