Hello, I am thinking of two orthopedic conditions that cause hip pain and inner thigh in children your grandson s age. One is slipped capital femoral epiphysis which more often occurs in obese children. This is when the very top of the long bone between the hip and knee slips. The other is Perthes disease in which blood supply is lost to the same part of this long bone in the leg. If his x-rays did not include views of his hips, then these diseases would not be found. My opinion is that if his pain is so severe that he needs a narcotic pain reliever then he should be evaluated by a pediatric orthopedist. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Arnold Zedd, Pediatrician