A 24-year-old female complains of chest pain and difficulty breathing. She tells you a horse kicked her in the chest. Her skin is pale and diaphoretic. You observe a contusion to the left side of her anterior chest wall. Breath sounds are absent over her left lower lung. Her vital signs are P 116, R 22, BP 92/80, and SpO2 is 95. What is the most likely diagnosis?
1) Pneumothorax
2) Pulmonary embolism
3) Myocardial infarction
4) Costochondritis