MSFinals-0698

A 35-year-old man presents to his GP with a complaint of rectal bleeding that has been going on for 2 days. The bleeding worsens after passing stools. He has recently increased his fibre intake, but he still finds it very difficult to pass stools. Defecation causes him severe pain that lasts for hours. During the examination, you try to perform a DRE, but the patient experiences severe pain, making it impossible to complete the procedure. What is the most probable diagnosis?