A 25-year-old female presents to you complaining of a chronic non-productive cough and episodic shortness of breath. The symptoms are usually worse in the early morning and are also made worse by exercise. You carry out a respiratory examination and you note an audible expiratory polyphonic wheeze on auscultation. You suspect asthma and send the patient for spirometry however, the results have returned as normal. What do you inform the patient?