Torsion : Ovarian and testicular torsion can present with flank pain.
[emdocs.net]
Chronic Pyelonephritis may come to attention during an episode of acute pyelonephritis with its attendant constitutional symptoms, flank pain, bacteruria, and pyuria.
[pathwaymedicine.org]
Patients typically present with flank pain, costovertebral angle tenderness, fever, and other features of cystitis (e.g., dysuria, frequency).
[amboss.com]