An unusual cause of rectal bleeding

What's causing this patient's frequent bowel motions and pain?
Dr Mabel Luo
Woman with stomach pain

Monica, a 32-year-old office clerk, presents to her GP with a three-month history of worsening intermittent rectal bleeding and dyschezia. 

She reports increased frequency of bowel motions, to about 3-4 times daily (typically 1-2 daily), sometimes associated with bloating and abdominal pain.