Final answer:
The nurse should call the provider immediately because the patient's symptoms may indicate a complication like stomach wall perforation.
Step-by-step explanation:
The nurse should a. call the provider immediately.
In this scenario, the patient with peptic ulcer disease suddenly experiences extreme pain and a rigid abdomen. These symptoms may indicate a complication like perforation of the stomach wall. Perforation is a medical emergency that requires immediate surgical intervention to repair the damage. Therefore, the nurse should call the healthcare provider immediately to inform them of the patient's condition.