The mother of the 12-month-old with cystic fibrosis reports that her child is experiencing increasing congestion despite the use of chest physical therapy (CPT) twice a day and has also experienced a loss of appetite. What instruction should the nurse provide?
A) "Continue with the current therapy regimen as it seems to be effective."
B) "Decrease the frequency of CPT to once a day."
C) "Increase the amount of solid foods in the child's diet."
D) "Notify the healthcare provider about the changes in symptoms and appetite."