Hi Karen, I would think that any healthcare provider worth his/her salt would welcome information such as this. I think a politely worded letter with information from The Spondylitis Association would be very good. I suggest The Spondylitis Association because this is an organization that is recognized and that being the case, if the information comes from them, I would think your PT would be less likely to discount it.
Here's their page on Undifferentiated Spondyloarthropathy.
Spondylitis Association Good luck.
Hugs,
