A 28-year-old unmarried woman presents to the emergency department with a 3-day history of lower abdominal pain, fever (38.5°C), and purulent vaginal discharge. She reports multiple sexual partners in the past 6 months and denies contraceptive use. On examination, she has cervical motion tenderness, adnexal tenderness bilaterally, and rebound tenderness. Urine pregnancy test is negative. Cervical swabs are sent for gonorrhea and chlamydia PCR. What is the most appropriate immediate management?