Dear S Thakral I am sorry to hearabout your mother. I think she is suffering from a condition which is called Post Herpetic Neuralgia. It is thought that to be due to nerve damage by herpes zostervirus as a result the affected area of the skinsendabnormal electrical impulses to thr brain of severe pain. The pain is variablefrom discomfort to extremely severe form and is like burning or stabbing in charecter.It starts after after herpes zoster rash and continued over three months.Ideally one should seek medical advisewith in three days after rash appears for the treatment of herpes zoster with antiviral antibiotics that reduces course of post herpetic neuralgia.I think ideally you should see a Dermatologist who will give her appropriate treatment.Herpetic neuralgia occurs 10% of peoples under 60 and 40% peoples over 60. The treatment for herpetic neuralgia are to reduce the pain from the site is to apply lidocane skin patches,aspirin mixed with diethyl ether,nonopied analgesic paracetamol, nonsteroid anti inflamatory drugs like ibuprofen, diclofinac, opieds tramadol, morphine ,fentanyl application of high consentrated capsicum ointment, antidepressant drugs like amitryptiline, venlafaxine; Anticonvulsant drugs likr carbamezapine, gabapentin, relaxation techniques, heat therapy, cold therapy, Transcutanious electrical nerve stimulator(TENS). most progress with slow restoration. Kindest regards.