have you asked your rheumy and pain doc if you have one? both of those have provided good references to me. if you call around you may want to avoid limiting to spondylitis expertise since this is very unlikely - instead look for people with deep knowledge in the part that needs therapy (e.g. pelvis)
Jen, 42, happy partner of James and Moma to Evan, 14, & Lucy, 12.5 (Crohn's dx @ age 3; on Remicade since April 2010.) I take piroxicam, Flexeril, & Nucynta ER nightly. 3 anti-TNFs didn't pan out for me.
"Science is the father of knowledge, but opinion breeds ignorance." -- Hippocrates