My Son Is Only 15 Years Old And Active. He

My son is only 15 years old and active. He play football. His lab results came back with his creatine levels high 1.66 and his urine came back with protein this Monday. He is now complaining of his back hurting and it appears to me his lower left side is inflammed. He isn't sure if he strained in it weight lifting or could this be related to his labs?
Thanks,
Sandy