Constipation: This is a common issue in children, often presenting with abdominal pain, and can be acute or chronic. The pain is usually crampy and may be accompanied by changes in bowel habits.

Viral Gastroenteritis: Common in children, it presents with abdominal pain, vomiting, and diarrhea. The symptoms are usually self-limiting but can lead to dehydration if not managed properly.
Urinary Tract Infection (UTI): While more common in girls, UTIs can occur in boys and present with abdominal pain, dysuria, and frequent urination.
Appendicitis: Although less common in younger children, appendicitis is a significant concern as it requires prompt surgical intervention. Symptoms include abdominal pain that may start around the navel and then move to the lower right abdomen, fever, and loss of appetite.
Functional Abdominal Pain: Part of functional gastrointestinal disorders, this condition is characterized by recurrent abdominal pain that is not explained by other medical conditions.

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 presents with severe abdominal pain, vomiting, and sometimes bloody stools.
Testicular Torsion: Although it presents with testicular pain, it can sometimes be perceived as abdominal pain. It's an emergency that requires immediate surgical intervention to save the testicle.
Pneumonia: Lower lobe pneumonia can cause referred abdominal pain, especially if the diaphragm is irritated. Symptoms include fever, cough, and difficulty breathing.
Diabetic Ketoacidosis (DKA): Presents with abdominal pain, vomiting, and signs of dehydration, along with hyperglycemia. It's a serious complication of diabetes that requires immediate medical attention.

Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can present with chronic abdominal pain, diarrhea, weight loss, and sometimes blood in the stool.
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 caused by various factors including gallstones, medications, or genetic conditions. Presents with severe abdominal pain, vomiting, and elevated pancreatic enzymes.
Ovarian Torsion: Though extremely rare in prepubertal boys, it's worth mentioning for completeness, as it can occur in the context of undescended testes or other anatomical abnormalities.