Don't give up!! I started having symptoms when I was 5yrs old and until I was 19yrs old they had NO idea what it was. I went to so many hospitals drs an specialists before finally finding a dr who did xrays and said ah ha it's AS! I'm very lucky my parents believed me and that they never gave up on taking me to dr after dr yo get answers and I thank them all the time for that. It's easier to fight for it if it's your children but remember you have to fight for this so you can be functional for your children. Hang in there and just keep pushing forward. Even if you say to the dr I'm not leaving your office until you give me a correct diagnosis. Be firm, be tough, demand the best because you deserve it. If you do not have insurance look around and call ask dr offices if they have a sliding scale for self pay. Many do.
Best of luck