You have unexplained pain in the lower back
The common backache that we know of often resolves after getting some rest. AS, on the other hand, comes with pain and motion issues that worsen right after waking up.
It’s advised to not work out when you have a backache, but AS symptoms could be mitigated after a quick session of exercise.
Moreover, lower back pain isn’t commonplace among young people. Therefore, adolescents and young adults should pay the doctor a visit if they complain of stiffness or pain in the lower back or hips.
Pain is most noticeable around the sacroiliac joints, where the pelvis meets the spine.