The causes of sudden leg pain in children are as follows: 1. Synovitis of the leg joints: Most often occurs after a cold, which can lead to sudden leg pain. 2. Epiphysitis: Mainly due to excessive force activities on the limb, or after cold, which can also lead to sudden leg pain. 3. Injuries to the leg joints or muscle strains: These can also lead to sudden leg pain symptoms. When children have sudden leg pain, they must consult a doctor to see what causes it and treat the cause to promote symptom reduction and recovery. When leg pain occurs, it is important to keep the legs warm and avoid excessive stress activities on the legs to avoid aggravating the pain. In daily life, you can eat more high-calcium, high-protein food, which can help to reduce the symptoms of leg pain.