Hi,
I don't know if you will see this because it has been so long since you made the original post.
My daughter, who is now 14, started complaining of back pain when she was about 6. Her ped couldn't find anything wrong, and he had her do all kids of things, so he did not refer her to an orthopediic surgeon. Last year she had really mono, and she was having a lot of hip pain. I took her to an ortho, and he did an MRI. Turns out she has spinal stenosis, like one might see in a 40 year old, according to the doc. She was extremely athletic, and the ortho said that he most often sees this type of thing in young athletes who are very intense and advanced for their age, and they impact their bodies in a way that their skeletal maturaty level cannot handle, and they end up with conditions like this. I describe all of this because I wonder, If your kid is extremely active, maybe he is overtaxing his skeletal structure as well. Anyway, he referred to PT, which she hasn't gotten around to doing yet, but I am sure will help based on my ownd experience with back pain. Need to strengthen and stretch.