Your mother is now passing through the phase of post herpes zoster neuralgia. This is a known sequel of this disorder. Greater the age of the patient, greater is its incidence and severity. This can be minimised by aggressive antiviral therapy started within first 72 hours, preferably in the first 48 hours. Most patients have pain, but some may have itching, sensation of insects crawling, numbness etc. With the passage of time, severity of neuralgia decreases and disappears. Medicines (like Tegretol) are given to make the patient comfortable and to help the patient tide over this phase. In an extremely rare case neurectomy may have to be done.