Varicella-zoster is a virus that causes chicken pox in children, and shingles in the adult. It typically causes intense pain and a blistering rash along the distribution of a sensory nerve, and may occur anywhere on the body surface, usually confined to the specific "dermatome" (the area served by a particular sensory nerve). Treatment involves the use of antiviral medication (e.g., acyclovir, valacyclovir) and pain medication.
Pain that is described as "sharp" or "shock-like" is suggestive of neuropathic pain, such as a neuralgia, but subjective symptoms are in themselves insufficient to establish a reliable diagnosis
. That is why if neurological issues are suspected, a formal neurological diagnostic protocol is needed.
The term "neurological disorder" in intended to refer to any disorder that may affect the brain, spinal cord, or peripheral nervous system. It could be anything from a neuropathy due to a medication or disease (for example, some medications are known to cause nerve damage, and some diseases, like diabetes, blood disorders, or nutritional deficiencies are known to damage the nerves). It could also be a primary neurological disease, such as multiple sclerosis or ALS. I used the term "neurological disease" in its broadest sense, to be all-inclusive, because I am not as a dentist qualified to provide guidance of a neurological nature.
Sores in the mouth are likewise difficult to identify simply by their presence. Often times they are just trivial canker sores, while other instances may reflect more serious mucous membrane disorder, such as Crohn's disease or lupus. These are matters that are best evaluated in person by a skilled clinician (dentist or ENT specialist).
If you were having pain, the usual recommendation would be to use an over the counter analgesic like ibuprofen until you could see your doctor. However, there is nothing that you could yourself if the predominant symptom is numbness. Proper management will depend on identification of the underlying cause for this symptom.
Hope this helps...