Constipation: This is a common cause of periumbilical pain in adolescents, often due to a low-fiber diet, dehydration, or poor bowel habits. The pain is usually crampy and accompanied by bloating, nausea, and changes in bowel movements.

Gastroenteritis: Viral or bacterial infections can cause inflammation of the stomach and intestines, leading to periumbilical pain, diarrhea, vomiting, and fever.
Irritable Bowel Syndrome (IBS): A functional gastrointestinal disorder characterized by recurrent abdominal pain, bloating, and changes in bowel habits, which can manifest as periumbilical pain.
Appendicitis: Although the pain typically starts near the navel and then moves to the lower right abdomen, some cases may present with periumbilical pain, especially in the early stages.

Intussusception: A condition where a part of the intestine telescopes into another, causing severe abdominal pain, vomiting, and bloody stools. It's a medical emergency that requires prompt diagnosis and treatment.
Midgut Volvulus: A twisting of the intestine that can cut off blood flow, leading to severe abdominal pain, vomiting, and potential bowel ischemia. It's a life-threatening condition that requires immediate surgical intervention.
Ectopic Pregnancy: Although rare in males, it's essential to consider this diagnosis in any patient with periumbilical pain, as a ruptured ectopic pregnancy can be fatal if not promptly treated.

Meckel's Diverticulum: A congenital anomaly of the small intestine that can cause periumbilical pain, gastrointestinal bleeding, or intestinal obstruction.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause chronic inflammation of the gastrointestinal tract, leading to periumbilical pain, diarrhea, and weight loss.
Abdominal Migraine: A condition characterized by recurrent episodes of severe abdominal pain, often accompanied by nausea, vomiting, and headache, which can be mistaken for other causes of periumbilical pain.