A 23-year-old man presents with a painful, swollen right knee following an arthroscopy 2 weeks ago. He has fever 38.5°C and limited range of motion. According to septic arthritis guidelines, what is the most appropriate immediate step?AStart oral NSAIDs only and review in a weekBArrange urgent joint aspiration for Gram stain, culture, and initiate empiric intravenous antibioticsCOrder MRI knee and wait for result before treatmentDTreat with oral antibiotics without aspirationEReassure; postoperative pain can be expectedCheck my answer