The ProblemA 32-year-old woman with a history of fibromyalgia and irritable bowel syndrome presents to you for evaluation of rectal pain of 3 weeks’ duration. She has had episodes of diarrhea alternating with constipation for years. Despite psyllium therapy, her stools have been hard and difficult to pass. During defecation 3 weeks ago, she developed excruciating pain that lasted for 60 minutes. Presently, she says it feels like she is passing “broken glass” with every bowel movement. She has...