Appendicitis: This is often the first consideration for right lower abdominal pain, especially if the pain started near the belly button and then moved. The proximity of the appendix to the right flank can sometimes cause flank pain to be associated with the condition.

Nephrolithiasis (Kidney Stones): Pain from kidney stones can radiate from the flank into the lower abdomen. The pain is often severe and can be accompanied by nausea, vomiting, and blood in the urine.
Pyelonephritis: An infection of the kidney, which can cause flank pain and lower abdominal pain, especially if the infection spreads or if there is an associated urinary tract infection.
Diverticulitis: Inflammation of a diverticulum in the colon, which can cause lower abdominal pain. If the diverticulum is located in the right colon, it might cause pain that radiates to the flank.

Ectopic Pregnancy: Although less common, an ectopic pregnancy can cause severe abdominal pain, including flank pain, and is a medical emergency.
Ruptured Aortic Aneurysm: A life-threatening condition that can cause severe abdominal and flank pain, often described as tearing or ripping.
Ovarian Torsion: A condition where the ovary twists around its ligaments, cutting off blood supply. It causes severe, sudden pain and is a surgical emergency.

Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodes of severe pain, including flank pain, along with other symptoms like hypertension and palpitations.
Retroperitoneal Hematoma: Bleeding into the space behind the peritoneum, which can cause flank and abdominal pain, often due to trauma or anticoagulation.
Right Colon Cancer: Although less common than left-sided colon cancer, right-sided colon cancer can cause abdominal pain, including flank pain, especially if the tumor is large or has spread.