Final answer:
The most important question for the nurse to ask is "What were you doing before the pain began?" The nurse can gather important information about the potential cause of the patient's symptoms by asking about their activity prior to the onset of symptoms.
Step-by-step explanation:
The most important question for the nurse to ask in this situation is "What were you doing before the pain began?"
This question is essential because it can help the nurse determine whether the patient's symptoms are related to a potential life-threatening event, such as a pulmonary embolism. By asking about the patient's activity prior to the onset of symptoms, the nurse can gather important information about the potential cause of the patient's shortness of breath and chest pain.