Is it normal to have stomach pain while taking tegretol for pain control?

It isn't . Common side effects of tegretol include nausea and vomiting. Stomach ache may be a sign of more serious condition - pancreatitis.
No direct answer. You would not know if the tegretol was or was not the cause of your stomach pain. See your primary care physician if you are having symptoms of stomach pain whether or not you are on tegretol.