Q. A 25-year-old man presents to the emergency department with a 2-week history of fever, nausea, and vomiting. He reports that he has also developed a diffuse rash and joint pain. He has a past medical history of hay fever, but no known drug allergies. On physical examination, the patient is febrile with a temperature of 38.5 degrees Celsius, blood pressure of 110/70 mm Hg, heart rate of 90/min, and a respiratory rate of 20/min. There is a diffuse erythematous rash over his entire body, and his skin is warm and tender to touch. Laboratory tests demonstrate eosinophilia in his blood. Urinalysis shows proteinuria, hematuria, and red blood cells casts. A renal function test shows creatinine level of 1.9 mg/dL (baseline 0.8 mg/dL). Imaging studies show diffuse patchy inflammation in the renal parenchyma. What is the most likely diagnosis?