Aphthous Ulcers: Recurrent aphthous ulcers are a common condition characterized by recurring ulcers on the tongue and other parts of the oral cavity. They can be associated with abdominal pain if the patient has an underlying condition like inflammatory bowel disease (IBD) that predisposes them to both aphthous ulcers and abdominal pain.

Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause both abdominal pain and oral manifestations, including tongue lesions. The connection between IBD and oral lesions is well-documented, making it a plausible diagnosis.
Behçet's Disease: This is a form of vasculitis that can cause a wide range of symptoms, including recurrent oral ulcers, genital ulcers, and gastrointestinal symptoms like abdominal pain. It's less common but should be considered in patients with a combination of these symptoms.
Celiac Disease: An autoimmune reaction to gluten can lead to malabsorption and various symptoms, including abdominal pain and potentially oral manifestations like aphthous ulcers, although the latter is less directly associated.

Lymphoma: Certain types of lymphoma, particularly those affecting the gastrointestinal tract or the oral cavity, can present with a combination of abdominal pain and tongue lesions. Although rare, missing a diagnosis of lymphoma could have severe consequences.
Systemic Lupus Erythematosus (SLE): SLE is an autoimmune disease that can affect multiple systems in the body, including the gastrointestinal system and the mucous membranes, leading to a variety of symptoms including oral ulcers and abdominal pain.
HIV/AIDS: Individuals with HIV/AIDS can experience a range of oral lesions, including ulcers, and may also have gastrointestinal symptoms due to the disease itself or opportunistic infections.

Eosinophilic Gastroenteritis: A rare condition characterized by the presence of eosinophils in the gastrointestinal tract, leading to abdominal pain and potentially oral manifestations, although the latter is less common.
Sweet Syndrome: Also known as acute febrile neutrophilic dermatosis, it can present with oral lesions and systemic symptoms including abdominal pain, though it is quite rare.
Patterson-Brown-Kelly Syndrome (Plummer-Vinson Syndrome): Characterized by esophageal webs, iron deficiency anemia, and oral lesions, it's a rare condition that could potentially cause some of the symptoms described, though abdominal pain is not a primary feature.