I had similar experience to OP. After 5 years and 20k USD spent for scattered pieces from various expensive specialists, I finally got diagnosed with AS at 27. This is not about aging at all. The disease (or disorder) doesn't have any known treatment, it only can be slowed down with expensive meds. The diagnosis is very tricky because the destructive effect - ossification of joints - happens slowly and mostly invisible on any type of modern (and expensive) imagery.