ONe question, has your son been seen by a BOARD CERTIFIED PEDIATRIC RHEUMATOLOGIST. This is critically important for a correct diagnosis. My son is 16 1/2 and was diagnosed at 12 with spondyloarthropathy and my daughter who is 18 was diagosed at 16 with the same thing. While this is not the same thing as AS, it is similar. If you would like to e-mail me, it is email@example.com.