ve been on Neurontin, I would highly doubt that the med is the culprit here. The symptoms you describe could be a result of a whole lot of things.
Anxiety,
for one, like you mentioned, you be the cause (or a contributing factor)...a virus...a simple change in your digestive patterns, GERD ("reflux"), etc etc.
Before you "decide" that the Neurontin is to blame, go to your doctor and have an assessment. Rule out other issues first. You may even have to give it some time..