Gastroenteritis: This is the most common cause of nausea, vomiting, and diarrhea, especially when symptoms are triggered by eating. It can be caused by viral or bacterial infections and is often self-limiting.

Food Poisoning: Similar to gastroenteritis, food poisoning can cause sudden onset of nausea, vomiting, and diarrhea after consuming contaminated food.
Irritable Bowel Syndrome (IBS): Although IBS is more chronic, some patients may experience acute exacerbations of symptoms, including diarrhea and nausea, especially after eating.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic diarrhea, nausea, and vomiting, which may worsen after eating.

Appendicitis: While appendicitis typically presents with abdominal pain, nausea, and vomiting, diarrhea can occasionally be a symptom. It's crucial to consider appendicitis due to the need for urgent surgical intervention.
Intestinal Obstruction: This condition can cause severe vomiting and may lead to diarrhea. It requires immediate medical attention to prevent complications.
Food Allergy or Intolerance: Severe reactions, such as those seen in food allergies, can present with gastrointestinal symptoms, including diarrhea and vomiting after eating specific foods.

Celiac Disease: An autoimmune reaction to gluten, leading to small intestine damage and causing chronic diarrhea, nausea, and abdominal pain after consuming gluten-containing foods.
Whipple's Disease: A rare, systemic bacterial infection that can cause malabsorption, leading to chronic diarrhea, weight loss, and abdominal pain.
Giardiasis: An intestinal infection caused by the Giardia parasite, which can lead to chronic diarrhea, nausea, and weight loss, especially in immunocompromised individuals or after travel to endemic areas.