A patient with gastroesophageal reflux disease (GERD) is being managed with a proton pump inhibitor (PPI). During a follow-up visit, the patient reports new- onset diarrhea and abdominal pain. What is the nurse's priority action in this scenario?

Advise the patient to use an over-the-counter antidiarrheal medication.

Assess the patient for signs of Clostridium difficile infection

Instruct the patient to discontinue the PPI immediately.

Recommend increasing fiber intake to manage diarrhea symptoms.