Reddit mentions of Ankylosing Spondylitis: The Facts (Oxford Medical Publications) (The Facts Series)

Your symptoms do sound like AS to me.

• X-Ray evidence can take a long time to appear, especially in the early stages. By the time X-ray evidence does appear, there is often irreversible damage. You want to be diagnosed as early as possible.
  
• Blood tests are often no help in diagnosis but can be used to rule out other diseases.
  
  • Over 30% of patients with AS will NOT have raised ESR value in blood tests, even when they have active inflammation.
    
  • A negative for Rheumatoid Factor (RF) means you do likely have it.
    
  • Many AS patients test negative C-Reactive Protein as well.
    
    Because of this, it can take 6-10 years to be diagnosed with AS. That's too long! Because of this, try to read and learn as much as you can about the disease so you can help guide your doctors.
    
    I found these two books to be very helpful:
    
    https://www.amazon.com/gp/product/0192632825/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
    
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    https://www.amazon.com/Ankylosing-Spondylitis-Michael-H-Weisman/dp/0195399102/ref=pd_bxgy_img_3/144-6520311-3143741?_encoding=UTF8&pd_rd_i=0195399102&pd_rd_r=67ca7118-73da-4683-9c85-004740e7f2ec&pd_rd_w=N8wVF&pd_rd_wg=LomRf&pf_rd_p=a2006322-0bc0-4db9-a08e-d168c18ce6f0&pf_rd_r=N367XZKSVJ5PFEQD1Y7H&psc=1&refRID=N367XZKSVJ5PFEQD1Y7H