Dear,
Positive HLA B27 is strongly associated with Ankylosing spondylitis and other inflammatory Spondyloarthropathies.
Symptoms for above conditions are: Low back pain, stiffness etc.
Next Steps
Get X-ray pelvis with both hips done, X-ray Lumbosacral spine.
Start physiotherapy, Hot fomentation.
Swimming is the best exercise method.
Health Tips
Get yourself examined and get your treatment started.