If you lose feeling in a particular part of your body, lose control of your muscles or have abnormal nerve sensations such unexplained pain, burning in your feet, tingling or itching, you usually have a neuropathy: nerve damage. Nerves can be damaged by something pinching or stretching them, such as excessive pressure from moving a limb repeatedly (as in carpal tunnel syndrome in your hand), scar tissue, or a disc problem in your back. Nerves can also be damaged by diabetes; lack of a vitamin (such as B12 in pernicious anemia); infections such as Lyme disease, shingles and herpes; poisonings by substances such as mercury or lead, or by diseases such as multiple sclerosis.
Pain in your thumb and three fingers next to it is usually caused by a pinched nerve in your palm called carpal tunnel syndrome, but all cases of neuropathy can be caused by generalized diseases. At the very minimum, your doctor should order a vitamin B12 level to check for pernicious anemia, a hemoglobin A1C to check for diabetes, a Lyme antibody to check for infectious diseases spread by tick bites, and herpes titers to see if you have had a recent infection with that virus. You should never ignore a neuropathy because many causes are controllable before you suffer permanent damage to your nerves. If you have diabetes, see my report on treatment of insulin resistance. If you have pernicious anemia, take B12 pills. If you have herpes, take acyclovir, and if you have Lyme disease, take long term antibiotics. If you have severe pain from your neuropathy, you can treat it with an anticonvulsant pill called Tegretol (200 mg three times a day) and topical 0.025% capsaicin cream three times a day.