Differential Diagnosis

The patient's symptoms of stomach sensitivity, gassiness, and urges during periods of nervousness, followed by persistent diarrhea after a year of consuming junk food, alcohol, and other substances, suggest several possible diagnoses. Here's a categorized differential diagnosis:

• Single most likely diagnosis
  • Irritable Bowel Syndrome (IBS): The patient's symptoms of abdominal sensitivity, gassiness, and altered bowel habits (diarrhea) in response to stress and dietary changes are classic for IBS. The condition is common and often triggered by stress, certain foods, and lifestyle factors.
• Other Likely diagnoses
  • Functional Dyspepsia: This condition involves recurring signs and symptoms of indigestion that have no obvious cause. Symptoms can include bloating, gas, and discomfort in the upper abdomen, which align with the patient's initial complaints.
  • Inflammatory Bowel Disease (IBD): Although less likely given the description, IBD (including Crohn's disease and ulcerative colitis) could present with chronic diarrhea and abdominal discomfort. The patient's history of consuming potentially irritating substances could have exacerbated symptoms.
  • Gastroesophageal Reflux Disease (GERD): GERD might cause some of the patient's symptoms, such as discomfort and bloating, especially if the patient experiences reflux.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Celiac Disease: An autoimmune reaction to gluten that can cause severe gastrointestinal symptoms, including diarrhea and abdominal pain. It's crucial to rule out celiac disease due to its potential for severe complications if left untreated.
  • Infectious Gastroenteritis: Persistent diarrhea could be due to a chronic infection, which needs to be identified and treated to prevent long-term consequences.
  • Colon Cancer: Although rare in young individuals, a change in bowel habits, especially if accompanied by other symptoms like weight loss or blood in stool, necessitates ruling out colon cancer.
• Rare diagnoses
  • Microscopic Colitis: A condition characterized by chronic, watery diarrhea, often without visible inflammation on standard endoscopy but with microscopic changes in the colon lining.
  • Bile Acid Diarrhea: A condition where the body produces too much bile acid, leading to chronic diarrhea.
  • Gastroparesis: A condition where the stomach takes too long to empty its contents, which can cause nausea, vomiting, feeling full after eating only a small amount of food, and bloating.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, and potentially, diagnostic tests to determine the underlying cause of their symptoms.