Final answer:
The client is experiencing a pulmonary reaction requiring cessation of the medication.
Step-by-step explanation:
The client is experiencing a pulmonary reaction requiring cessation of the medication. Nitrofurantoin is associated with a rare but serious pulmonary reaction known as nitrofurantoin-induced lung injury. Symptoms of this reaction can include cough, chills, fever, and difficulty breathing, which are consistent with the client's complaints. If the client is experiencing these symptoms, it is important to stop the medication and seek medical attention immediately.