A 70-year-old male with a 20-year history of chronic cough and sputum production lasting 3-4 months annually, experiencing exertional dyspnea for the past 2-3 years and occasional bilateral lower extremity edema. This morning, he suddenly developed sharp left upper chest pain related to respiration, followed by dyspnea, profuse sweating, and inability to lie flat. The most critical aspect of history-taking should be: