Question category: Gastroenterology
A 55 year old gentleman was discharged one week ago following treatment for neutropenic sepsis. He has been having chemotherapy for colorectal carcinoma. He now presents with watery diarrhoea although he has had some blood stained stools and abdominal cramps. He looks unwell and is hypotensive and tachycardic. He has generalised abdominal tenderness although there is no evidence of peritonism. Bloods reveal an elevated CRP and normal WCC. Which of the following is the most likely diagnosis?