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?

Recommend increasing fiber intake to manage diarrhea symptoms

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

Instruct the patient to discontinue the PPI immediately.

Assess the patient for signs of Clostridium difficile infection.