If neurontin has helped in the past to relieve your symptoms, which it sounds like it does, this suggests that your pain is neuropathic, meaning arising from the nerves.
Neurontin dosing may need adjusting which you should discuss with your physician.
(2) If symptoms migrate (move from one place to the other) and are intermittent, causes might include seizures, migraine disorder or metabolic problems such as low calcium.