You're doing a medicine rotation when you get consulted by trauma surgery. The patient is a diabetic with known heart failure who got into a motor vehicle accident one day ago. Several serial CT scans yesterday afternoon ruled out any surgical emergency and he was admitted for observation. He was not hypotensive or in shock. This morning, his creatinine reaches 4mg/dL. You call his primary medical doctor and find that his baseline creatinine is 2mg/dL. He has not gotten any new medications.
Challenge: What's the most likely diagnosis?