Lactose Intolerance: This is the most likely diagnosis because lactose intolerance is a common condition where the body is unable to digest lactose, a sugar found in milk, due to a deficiency of the enzyme lactase. Symptoms include bloating, gas, diarrhea, and stomach grumbling after consuming lactose-containing products.

Irritable Bowel Syndrome (IBS): IBS can cause similar symptoms to lactose intolerance, including abdominal pain, bloating, and changes in bowel movements. While it's not directly related to milk consumption, some people with IBS may experience worsening symptoms after eating certain foods, including dairy.
Milk Protein Allergy or Intolerance: An allergy or intolerance to milk proteins (casein or whey) can cause gastrointestinal symptoms similar to lactose intolerance, including stomach grumbling, diarrhea, and abdominal pain.
Gastroesophageal Reflux Disease (GERD): Although not directly related to milk consumption, GERD can cause stomach discomfort and grumbling, especially after eating. Some foods, including dairy, can trigger or worsen GERD symptoms in some individuals.

Celiac Disease: An autoimmune disorder where the ingestion of gluten leads to damage in the small intestine. It can cause gastrointestinal symptoms similar to lactose intolerance, including abdominal pain, diarrhea, and bloating. While not directly related to milk, celiac disease is important to diagnose due to its potential for long-term complications if left untreated.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic inflammation of the gastrointestinal tract, leading to symptoms that might be confused with lactose intolerance, such as abdominal pain, diarrhea, and weight loss. Early diagnosis and treatment are crucial to manage the disease and prevent complications.

Galactosemia: A rare genetic disorder that affects how the body processes a type of sugar called galactose. A major source of galactose is lactose, found in milk. Symptoms can include feeding difficulties, failure to thrive, and liver dysfunction, among others.
Fructose Malabsorption: Although more related to the consumption of fructose (a sugar found in many fruits, vegetables, and added sugars), some individuals might experience overlapping gastrointestinal symptoms that could be confused with lactose intolerance, especially if they consume products that contain both lactose and fructose.