Holly,
My Mom also had a sore arm and then about two months ago she lost use of it completely. It was really an overnight thing, but she complained of pain and soreness for awhile and thought it was arthiritis, she is 62. My Mom is a 2 1/2 year survivor of GBM, she is now losing her battle with the cancer. She had done a ton of different clinical trials and we believe this is what has kept her alive so long. Now we are hoping that the final stages of her life are comfortable and surrounded by everyone she loves.
Good luck Holly.
Mommgbm60