The history provided by you is not complete, but still, if i presume the following findings as told by you,
if your mother is not having any sort of blisters (fluid filled elevated pimples
) or ulcers in her oral cavity along with any sort of fever
when pain occurs, and if the pain is restricted to left side of the jaws, the most likely diagnosis is TRIGEMINAL NEURALGIA
treatment of TN is by both medicinal and surgical. the medicine which she is taking right now, is one of the most recommended. She can continue with that, Still, if pain is increasing, then you can consult with a good Oral and maxillofacial Surgeon, who after the proper scanning examinations can opt for Peripheral Neurectomy
Procdures, done routinely in day care surgeries.
TN is absolutely painful condition, in which pain often occurs after touching of certain specific area in oral cavity, known as Trigger Zones. if your mother is able to identify any of these, kindly tell her to avoid touching them