Which diagnosis is most likely given a patient presenting with a cough, headache, and wheezing for a week with clear lungs after coughing?

The diagnosis of acute bronchitis is the most likely given this patient’s symptoms of a cough, headache, and wheezing, especially since the lungs are clear upon examination after coughing. Acute bronchitis typically presents as a persistent cough that may last for weeks, often following a respiratory infection or exposure to irritants. The wheezing can occur due to airway inflammation and constriction common in bronchitis.

The fact that the patient's lungs are clear suggests that there is no significant obstruction or fluid accumulation typically seen in conditions like pneumonia. In pneumonia, you would generally expect to hear abnormal lung sounds, such as crackles, due to fluid in the alveoli.

Emphysema and asthma involve chronic airway issues, with emphysema characterized by long-term lung damage and reduced airflow over time, often with a history of smoking. Asthma typically presents with more severe wheezing and may include a history of episodic exacerbations, which doesn't align as closely with the patient’s current acute symptoms. Thus, acute bronchitis is the diagnosis that best fits the symptom profile presented.