A 30-year-old man presents with back pain and morning stiffness that improves with exercise. The pain is predominantly in the lower back and has been present for over three months. What could be the possible diagnosis and next steps?
The symptoms of chronic low back pain and stiffness improving with exercise but not with rest in a young adult may suggest ankylosing spondylitis. The next steps should involve blood tests including HLA-B27 antigen and inflammatory markers (CRP, ESR), along with imaging, potentially including X-rays and MRI of the sacroiliac joints and spine.