Problem:

Professor John Doe has a chest cold that won't go away, so his physician prescribes a course of antibiotics to help clear his bronchitis. Towards the end of the two-week course of antibiotics, Professor Doe begins to experience symptoms of irritable bowel syndrome. He finishes the antibiotics and his bronchitis completely clears, but his gastrointestinal symptoms continue to worsen so he makes another appointment with his physician. Together, they determine that he is not allergic to the antibiotic, however a biopsy reveals considerable inflammation of his jejunum and his physician diagnoses it as a mild form of Crohn's disease. When asked about his diet, Professor Doe indicates that he has made no major changes to the foods he eats. After a few more weeks, the symptoms disappear on their own.

Required:

Question: What might have happened to Professor Doe? Explain, giving as much detail as possible (come up with a potential mechanism).

Include source of information for best answer.