Gastroenteritis: This is often the most common cause of loose stools, typically resulting from a viral or bacterial infection. The sudden onset of symptoms, including diarrhea, vomiting, and abdominal cramps, supports this diagnosis.

Irritable Bowel Syndrome (IBS): Characterized by chronic abdominal pain, bloating, and alteration of bowel habits, IBS is a common condition that can cause loose stools, especially in individuals with a history of stress or certain dietary triggers.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic diarrhea, abdominal pain, and weight loss. While less common than gastroenteritis or IBS, IBD should be considered, especially with persistent symptoms.
Lactose Intolerance: The inability to digest lactose, a sugar found in milk and other dairy products, can lead to loose stools, gas, and bloating after consuming lactose-containing foods.
Food Poisoning: Similar to gastroenteritis, food poisoning from consuming contaminated food can cause sudden onset of diarrhea, vomiting, and abdominal cramps.

Clostridioides difficile (C. diff) Infection: A potentially life-threatening condition that can cause severe diarrhea, especially in individuals who have recently used antibiotics. Early diagnosis and treatment are crucial.
Cholera: While rare in many parts of the world, cholera is a highly infectious disease that causes severe, watery diarrhea and can lead to rapid dehydration and death if not promptly treated.
Giardiasis: An intestinal infection caused by the parasite Giardia, which can lead to severe diarrhea, dehydration, and malabsorption if left untreated.

Whipple's Disease: A rare, systemic bacterial infection that can cause diarrhea, weight loss, and abdominal pain, among other symptoms.
Short Bowel Syndrome: A condition that results from a significant loss of intestinal tissue, leading to malabsorption and chronic diarrhea.
Microscopic Colitis: An inflammatory condition of the colon that can cause chronic, watery diarrhea, often in older adults.
Thyroid Disorders: Both hyperthyroidism and hypothyroidism can cause changes in bowel habits, including loose stools, though this is less common and usually accompanied by other systemic symptoms.