[Expert Solution]: David presents with frequent episodes of…

David presents with frequent episodes of bloody diarrhea — up to 20 times a day during flare-ups — accompanied by severe abdominal cramping, unintended weight loss, and chronic fatigue. He describes the pain as a deep, cramping sensation primarily in the lower right abdomen, though it sometimes shifts. History of Present Illness: Symptoms began subtly 3 years ago with occasional loose stools and discomfort. Over time, the frequency and severity escalated. He now experiences episodic flareswhere the symptoms become unmanageable, often resulting in hospitalization for dehydration, anemia, and pain management. He reports: Persistent fatigue Low-grade fevers during flares Night sweats Loss of appetite Oral ulcers Joint pain in knees and ankles Painful skin nodules on his shins Redness and irritation in both eyes A recent colonoscopy revealed areas of patchy inflammation, deep ulcerations, and narrowed segments of the bowel, particularly in the terminal ileum and ascending colon. A biopsy was taken, but results are pending. Blood tests show elevated inflammatory markers (CRP, ESR), low hemoglobin, and low serum albumin. Past Investigations: Multiple stool cultures have been negative for infectious agents. Imaging (CT enterography) showed bowel wall thickening and a fistula forming near the terminal ileum. David has tried over-the-counter antidiarrheals and dietary modifications with minimal success. His condition continues to fluctuate unpredictably, greatly impacting his quality of life and work. Guided Questions: What are the key clinical and investigative findings that help narrow down a differential diagnosis for David’s condition? What diagnostic tests or procedures could confirm the suspected diagnosis? How would you differentiate this disease from other causes of chronic diarrhea like ulcerative colitis, IBS, or infections?