Common sports injuries in Young

Calcaneal Apophysitis:
Young children. 

Shin Splint (Medial Tibial Stress Syndrome)
pain along medial aspect of tibia

Patellofemoral Stress Syndrome
tenderness over medial facet of medial patella. 
due to poorly developed vastus medialis and tight hamstrings.

Quadriceps Contusion
pain in thigh.
palpable mass at site of pain
Complication: myositis ossificans

Rotator Cuff Tendinosis

Lateral Ankle Sprain

Spondylolysis

Medial Epiphysitis (Apophysitis)
Tennis elbow is rare in children, hence exlude fracture before making this diagnosis

Iliac Apophysitis
pain in iliac crest

Iliotibial Band Friction Syndrome (Iliotibial Band Bursitis)

Reference:
LAIRD HARRISON, Elsevier Global Medical News, Tackling the Top 10 Sports Injuries