Most teaching hospitals have a rheumatologist on their staff. Or they can refer you to one, that is where I would start. After a thorough examination, x-rays, MRI and an hla marker test, a good rheumatologist can determine a diagnosis. It took a long time for me to get an answer, about 20 years. Finally, when the first doctors were training in rheumatology, I was finally referred to one by my orthopedic doctor. While getting a diagnosis of AS is not an occasion for joy, it did point me to a treatment plan, and allowed me to live a productive life. Now at age 79, I am starting to decline in mobility, but I am going to try to stay positive and make use of the occasional day or two of remission before the next flare incapacitates me.