Hi paddington ,
A lot of those symptoms have been associated with low vitamin D. . Have you been checked for that?
In the UK , especially winter and early spring we can have low levels due to insufficient UVB in sunlight. Also modern western foods are low in VitD. Especially a vegetarian diet or vegan particularly.( unless artificially fortified).
Some research on AS strongly points to low levels of VitD being associated with it.
Here is one
academic.oup.com/rheumatology/article/57/suppl_3/key075.401/4971303
A collection of research over the last few years , can be found here.
vitamindwiki.com/Ankylosing+spondylitis+and+low+vitamin+D+%E2%80%93+several+studies
Bearing all that in mind , and your symptoms , I would get my VitD level checked. Either ask your doctor , or get a private test. IF it is low , i.e. below 75 nmol/L I would supplement to raise it.
There is an NHS lab , that will do tests for patients, but if not doctor ordered they charge £29. <a class="break-all" href="https://www.vitamindtest.org.uk/" rel="nofollow" target="_blank">www.vitamindtest.org.uk/</a>
I have posted quite a bit about Vit D here on Mumsnet ,
here is a long thread , with many people with similar symptoms, have a look see if you recognise yourself there. I tried to explain why we are very often low , and how we can improve things.
<a class="break-all" href="https://www.mumsnet.com/Talk/general_health/2841497-If-you-are-vitamin-D-deficient-what-have-you-been-prescribed" target="_blank">www.mumsnet.com/Talk/general_health/2841497-If-you-are-vitamin-D-deficient-what-have-you-been-prescribed</a>
Best of luck . Hope that info might prove helpful.
IF you need any more info , just get back .
BTBH.