A 37-year-old woman presents with worsening dyspnea and an intermittent, non-productive cough for 3 months. She had been physically active, but has had to stop her exercise routine. Over the past week she has begun needing to rest after climbing the stairs in her home. There is no history of wheezing, nocturnal aggravation of the cough, orthopnea, or paroxysmal nocturnal dyspnea. While there is no history of fever or loss of weight, she does complain of feeling lethargic since the onset of symptoms. She also noticed a transient, painful erythematous rash over her shins for the last six months. Her medical and surgical histories are unremarkable. She does not smoke, and has no family history of lung disease.