Hot Swollen Knee with Fever

Walter is a 62-year-old male presenting with acutely hot, swollen, severely painful right knee with fever, unable to bear weight. This started about a day and a half ago. My right knee began to ache, and then over just a few hours it swelled up enormously and turned red and hot to the touch. The pain is the worst I've ever had in that joint — easily a ten out of ten — and even the tiniest movement or a bedsheet touching it makes me cry out. Your task is to take a focused history from this patient.