Differential Diagnosis

• Single most likely diagnosis:
  • Irritable Bowel Syndrome (IBS): The patient's symptoms of abdominal pain, changes in bowel habits (diarrhea, loose stools), gas, and urgency, especially triggered by certain foods (high FODMAP) and stress, are classic for IBS. The onset after a significant life event (birthday party with excessive alcohol and unusual food intake) and the absence of infectious causes (negative stool tests) further support this diagnosis.
• Other Likely diagnoses:
  • Post-Infectious IBS (PI-IBS): Although the stool tests were negative, the onset of symptoms after a bout of diarrhea (potentially infectious, despite negative tests) could suggest PI-IBS. The patient's history of having some symptoms during stressful periods (10&12 board exams) that resolved, only to have them return after another significant event, might indicate a predisposition to IBS that was triggered by an infectious event.
  • Functional Dyspepsia: Overlapping symptoms such as abdominal pain and discomfort could also suggest functional dyspepsia, especially given the trigger of eating certain foods (like chilli paneer, hash brownie) and the initial onset after a night of poor sleep and excessive alcohol.
• Do Not Miss diagnoses:
  • Inflammatory Bowel Disease (IBD): Although less likely given the negative tests and the specific triggers (food, stress), IBD (Crohn's disease, ulcerative colitis) must be considered due to its potential severity and the need for early intervention. The presence of persistent diarrhea, abdominal pain, and the impact on daily life necessitate ruling out IBD.
  • Celiac Disease: Given the patient's reaction to certain foods and the presence of gastrointestinal symptoms, celiac disease should be considered, especially if the patient has not been tested for it. The disease can present with similar symptoms and is important to diagnose due to its implications for long-term health and management.
• Rare diagnoses:
  • Small Intestine Bacterial Overgrowth (SIBO): This condition could explain the patient's gas, bloating, and abdominal pain, especially if high FODMAP foods exacerbate symptoms. However, it's less common and typically considered after other diagnoses have been ruled out.
  • Fructose Malabsorption or other Carbohydrate Malabsorption: Given the patient's reaction to sugarcane juice and other potential high FODMAP foods, malabsorption issues could be a contributing factor, though less likely as a primary diagnosis.