Chest Film Clinic: What caused progressive dyspneain this patient with chronic asthma?

A 51-year-old man with a 20-year history of asthma and seasonal allergies presented with low-grade fever, progressive dyspnea on exertion, and wheezing that had persisted for 2 weeks. Four days earlier, he had been seen by his primary care physician and had started levofloxacin therapy. However, his respiratory symptoms had worsened, warranting hospitalization. He also reported pain in the abdomen and left flank and pain and swelling in the right metacarpophalangeal and right shoulder joints.