You are seeing a 45-year-old female in A&E who has presented with abdominal pain. During the history, the patient informs you that this pain came on suddenly 6 hours ago, is severe, constant and located in the right upper quadrant. The patient is also complaining of nausea and has vomited three times since the pain came on. On examination you note tenderness in the right upper quadrant on palpation which is made worse when the patient breaths in. The patient’s observations are all within normal limits aside from temperature which is elevated at 38.3 degrees. What is the most likely diagnosis?