On top of the already mentioned possibilities, there is such a thing as chemo-induced arthritis. For a while my mom was getting it in her hands, wrists, and arms. It seemed associated with her Temodar rounds. You can "google" it and find other sources/discussions regarding this.
:0) Nikki
59yo Mom Dx 10/07 plum-size GDM, resected; 6wks rad/Temodar; Temodar rounds x4; Gamma Knife 5/08 for small regrowths; 7/08 MRI no active tumor sites at this time; lives with my family