Aaron: I, too suffered from trigeminal neuralgia until I had my amalgams replaced.
This article may be helpful for your mother.( If I didn't know better, I would have thought this article was about me!)

Trigeminal neuralgia linked to amalgam fillings
JACKSONVILLE, FLORIDA. Dr. William Cheshire, a physician at the Mayo Clinic, reports on a case where a woman's trigeminal neuralgia (tic douloureux) was traced to a galvanic reaction between an amalgam filling and an adjacent gold-alloy crown. Consumption of tomatoes and other acidic foods produced intense jolts described as being like those of an "electrical battery". The jolts in turn resulted in excruciating pain in the trigeminal nerve. Replacing the amalgam filling with a composite resolved the problem. Dr. Cheshire points out that dissimilar metals in contact with saliva can form a galvanic cell which can generate electrical currents with several hundred millivolts of potential. He points out that many patients with trigeminal neuralgia describe their pain in terms of "electrical" jolts and concludes that his patient's neuralgia may well have been triggered by the galvanic reaction between the amalgam filling and the gold crown.

Before I had the amalgams replaced, I learned to avoid any tomato products, and the pain stopped! Perhaps your mother could try the same thing?