You are seeing a 45-year-old female in A&E who has presented with abdominal pain. The patient informs you that this pain is severe, intermittent and is located in the right upper quadrant. The patient also informs you that this pain lasts for around 60 minutes at a time. The patient has a temperature of 38.3 degrees, and you note tenderness in the RUQ on examination. What is the most likely diagnosis?