You first need to find out if you have an inflammatory spondyloarthropathy. Just because you are HLA B-27 positive does not mean that you have any of these inflammatory disorders.
There are blood test still to be performed like CBC, ESR and CRP. If these are negative, you might just have typical degenerative disc changes
The most common way to further your diagnosis is with an X-ray and possibly an MRI of your sacroiliac joints as this is the first place many of these disorders present.
NSAIDs are one of the medication used to treat this. There might be anti-immune medications if you do have an inflammatory disorder. These are administered by a rheumatologist.
Dr. Corenman