A 35-year-old woman is brought to the emergency department because of an 18-hour history of severe pain, nausea, vomiting, diarrhea, and anxiety. She was discharged with a pain medication from the hospital 2 weeks ago after treatment of multiple injuries sustained in a motor vehicle collision. She took her last dose 36 hours ago. Her temperature is 36.6°C (97.8°F), pulse is 105/min, respirations are 24/min, and blood pressure is 160/85 mm Hg. Physical examination shows rhinorrhea and piloerection. Bowel sounds are normal. She rates the pain as an 8 on a 10-point scale. Which of the following is the most likely diagnosis?