My Child 12 Years Old Tested For ASO Positive-800 IU/ml

my child 12 years old tested for ASO Positive-800 IU/ml , ESR 63 mm/hr, CRP 32.,vitamen D 25 nmol/L and URIC acid 3.51mg/dl. He is feeling pain in ankles, neck and most of all joints and moving one place to another. The doctor advice to take ospen 400 for 2 months and also Vitamin D tablets. Pl advice what is the seriousness of this illness, is it curable and what is the precaution to be taken in future to avoid complication.