Urinary Tract Infection (UTI): This is the most common cause of urinary symptoms in children, including urgency and frequency. The age and symptoms of the child make UTI a highly probable diagnosis.

Overactive Bladder: A condition characterized by a sudden, intense urge to urinate, often with frequency and nocturia. It's common in children and can be managed with behavioral therapy and medication if necessary.
Constipation: Chronic constipation can cause urinary urgency and frequency in children due to the proximity of the rectum to the bladder and urethra, leading to pressure and irritation.
Dietary Factors: Consumption of certain foods and drinks (e.g., caffeine, spicy foods, artificial sweeteners) can irritate the bladder, leading to urgency and frequency.

Diabetes Mellitus: Although less common, new-onset diabetes can present with urinary frequency and urgency due to the high glucose levels in the urine. Missing this diagnosis could lead to serious complications.
Neurogenic Bladder: A condition resulting from a neurological condition affecting bladder control, which could be due to spinal cord injuries, spina bifida, or other neurological disorders. Early diagnosis is crucial for appropriate management.
Kidney Stones: Though rare in young children, kidney stones can cause severe pain, urgency, and frequency. They require prompt medical attention to prevent complications.

Tuberculosis of the Urinary Tract: A rare condition in children, but it can cause chronic urinary symptoms including urgency and frequency. It's more likely in areas where TB is prevalent.
Bladder Tumors: Extremely rare in children, but they can cause urinary symptoms. Early detection is key to successful treatment.
Interstitial Cystitis: A chronic condition causing bladder pressure, bladder pain, and sometimes pelvic pain. It's rare in children but should be considered if other diagnoses are ruled out.