Gosh, I'm so sorry to hear that Sydney is feeling so poorly. I'm just catching up with things here on PT.

I think the cancer would show up on the blood tests, so I hope that the cancer is still in remission and that there is just another reason as to why she is not feeling well. Hopefully it is just something easy to fix and will not be anything long term or degenerative in nature.

Big hugs to you and to Sydney. All my good thoughts and hopes are going out to you.