Growing Pains: This is a common condition in children, characterized by recurrent leg pain, typically in the calves or thighs, that occurs in the late afternoon or evening. It is usually bilateral and can be related to growth spurts.

Muscle Strain: Given the age and potential for physical activity, muscle strain from overuse or injury is a plausible cause of leg pain in a child.
Infection (e.g., Osteomyelitis, Septic Arthritis): Though less common, infections can cause significant pain and are important to consider, especially if there's a history of trauma, fever, or other systemic symptoms.
Trauma: Fractures or soft tissue injuries from falls or other accidents can cause leg pain and are common in active children.

Child Abuse: It's crucial to consider non-accidental trauma, especially if the history provided does not match the injury, or if there are other signs of abuse.
Cancer (e.g., Leukemia, Bone Tumors): Though rare, cancers can present with bone or joint pain and must be considered, especially with persistent, unexplained pain, or systemic symptoms like weight loss or fatigue.
Neurological Conditions (e.g., Peripheral Neuropathy, Spinal Cord Tumors): Conditions affecting the nerves or spinal cord can cause leg pain and are critical to diagnose early for appropriate management.

Juvenile Idiopathic Arthritis (JIA): An autoimmune condition that can cause joint pain and swelling, JIA is less common but should be considered, especially with morning stiffness or swelling.
Legg-Calve-Perthes Disease: A condition affecting the hip joint, causing pain and limping, typically in children aged 4-8 years.
Slipped Capital Femoral Epiphysis (SCFE): A hip condition that occurs in late childhood and early adolescence, causing hip or knee pain and limping.