Lillian,
I am not a Dr ei8ther but what Angi says sounds plausable. The tumor could be pressing on a nerve causing this numbness and tingling. Did your mom go ahead and start the first rounds of her chemo? If so, this could also be something called neuropathy which is caused by the chemo. So you should call and ask her Dr about it.
Chris
Hi, Im no expert but it sounds like something is irritating a nerve, I would call her Doctor to get it checked out.
Best wishes
Angie