A 52-year-old woman with a history of chronic pancreatitis comes to the emergency department because of a 4-week history of worsening abdominal pain and diarrhea. Physical examination shows signs of malnutrition. The electrolyte panel shows potassium 2.9 mEq/L (3.5-5.0). The patient is admitted, electrolyte levels are corrected, and her symptoms controlled, allowing her to start eating. However, three days later, she starts complaining of fatigue, becomes tachypneic, and her oxygen levels drop. Physical examination shows a normal heart and lung auscultation, and an electrolyte panel shows phosphate 2.0 mg/dL (3.0-4.5). What is the most likely diagnosis?