Hi! Have you called the vet about Todo's symptoms? Willie (my Westie) hasn't had any unusual body movements that I can link to piroxicam. He has always "chased bunnies" as I call it in his sleep but I don't think that's what you are referring to in Todo's case. We haven't tried chemo. Stomach issues, such as vomiting, blood in stool, not eating, can be caused by piroxicam. I can't remember which stomach protectors you are using for Todo. I use Pepcid, Carafate and Pepto Bismol for Willie every day.
I'll be thinking of you & Todo and hoping for the very best!
Sue