Irritable Bowel Syndrome (IBS): This condition is characterized by chronic abdominal pain, bloating, and alteration of bowel habits in the absence of any mechanical, inflammatory, or biochemical abnormalities. The symptoms can persist or worsen despite the elimination of common allergenic foods like cow's milk, soy, egg, and peas, making it a likely diagnosis in this scenario.

Fructose Malabsorption: Some individuals may experience symptoms similar to those of food allergies or intolerances due to the inability to properly absorb fructose, a common sugar found in many foods. Eliminating fructose or reducing its intake might be necessary to alleviate symptoms.
Wheat or Gluten Sensitivity: While not an autoimmune disease like celiac disease, some people may experience symptoms after consuming wheat or gluten, which could explain the persistence of symptoms after eliminating other common allergens.
Other Food Intolerances: Intolerances to foods such as nuts, fish, shellfish, or certain spices could also be responsible for the ongoing symptoms.

Celiac Disease: An autoimmune disorder where the ingestion of gluten leads to damage in the small intestine. It's crucial to rule out celiac disease, as untreated cases can lead to severe complications, including malnutrition and increased risk of other autoimmune diseases.
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 not improve with dietary restrictions alone. Missing these diagnoses could lead to significant morbidity.
Gastrointestinal Infections: Chronic infections, such as giardiasis, can cause persistent gastrointestinal symptoms that do not respond to dietary changes.

Eosinophilic Gastroenteritis: A rare condition characterized by the presence of eosinophils in the gastrointestinal tract, leading to inflammation and symptoms that can mimic food allergies or intolerances.
Mastocytic Activation Syndrome: A condition involving the accumulation of mast cells in various tissues, including the gastrointestinal tract, which can lead to a wide range of symptoms, including those related to food intake.
Gastroparesis: A medical condition that affects the normal spontaneous movement of the muscles (motility) in your stomach. Normally, strong muscular contractions propel food through your digestive tract. However, in gastroparesis, motility is slowed down or doesn't work at all, leading to delayed stomach emptying.