Urinary Tract Infection (UTI): This is the most common cause of bad urine smell in children, and vaginal discharge can be a secondary symptom due to the proximity of the urethra and vagina. UTIs are more common in girls due to their shorter urethra.

Vaginitis: This condition, often caused by poor hygiene, irritation, or infection, can lead to vaginal discharge and may also cause a strong odor. It's common in prepubertal girls.
Foreign Body in the Vagina: Young girls may insert small objects into their vagina, leading to a foul-smelling discharge. This condition requires prompt diagnosis and removal of the object to prevent further complications.
Diabetes Mellitus: Although less common, new-onset diabetes can cause a sweet-smelling urine odor due to ketones, and vaginal discharge can be a secondary symptom due to yeast infections, which are more common in diabetic patients.

Sexual Abuse: Although not likely, it's crucial to consider sexual abuse in any case of vaginal discharge or unusual odor in a child, as it can have severe physical and psychological consequences if not addressed promptly.
Kidney or Bladder Stones: These conditions can cause a strong urine smell and, in rare cases, might lead to secondary infections causing vaginal discharge. They are less common in children but can be very painful and require immediate medical attention.

Congenital Anomalies of the Genitourinary Tract: Certain rare congenital conditions can lead to abnormal urine flow or vaginal discharge, causing a bad smell. These conditions are usually identified early in life but can sometimes present later in childhood.
Tumor or Cancer: Although extremely rare in children, tumors of the urinary or reproductive system can cause changes in urine smell or vaginal discharge. Early detection is crucial for effective treatment.