Constipation: This is a common issue in children, often presenting with abdominal pain, and can be due to various factors such as diet, hydration, or bowel habits.
Viral Gastroenteritis: Also known as stomach flu, it's a frequent cause of abdominal pain in children, usually accompanied by vomiting and diarrhea.

Appendicitis: Although not the most common, it's a significant consideration due to its potential for serious complications if not promptly treated. Symptoms can include pain that initially is diffuse and then localizes to the right lower quadrant.
Urinary Tract Infection (UTI): Can cause abdominal pain, especially if the infection involves the kidneys. Symptoms might also include dysuria, frequency, and fever.
Functional Abdominal Pain: Part of functional gastrointestinal disorders, this can include irritable bowel syndrome (IBS), functional dyspepsia, and abdominal migraine, which are common in pediatric populations.

Intussusception: A condition where a part of the intestine slides into an adjacent part, potentially cutting off blood flow. It's a medical emergency and can present with severe abdominal pain, vomiting, and bloody stools.
Midgut Volvulus: A twisting of the intestine that can cut off blood flow, requiring immediate surgical intervention. Symptoms can include severe abdominal pain, vomiting, and abdominal distension.
Pneumonia: Lower lobe pneumonia can refer pain to the abdomen, making it a "do not miss" diagnosis due to its potential severity and the need for prompt antibiotic treatment.
Diabetic Ketoacidosis (DKA): Can present with abdominal pain, nausea, vomiting, and is a medical emergency requiring immediate treatment to prevent serious complications.

Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis are less common in children but should be considered, especially with chronic abdominal pain, weight loss, and changes in bowel habits.
Henoch-Schönlein Purpura (HSP): A form of vasculitis that can cause abdominal pain, along with a characteristic rash, joint pain, and sometimes kidney involvement.
Pancreatitis: Inflammation of the pancreas, which can be due to various causes including gallstones, medications, or systemic diseases. It's rare in children but can cause severe abdominal pain.
Ovarian Torsion: A gynecological emergency that can cause severe abdominal pain, usually in prepubescent or adolescent girls, and requires immediate surgical intervention.