What Causes Numbness In Legs And Hands?

What would be the possible reason why I would have trouble walking? My legs felt like they were not there and I was not touching the ground with my feet. This lasted just a few minutes but I felt slow and unbalanced. I have also. Been experiencing a numb hand which can be painful at times. I have a EMG scheduled for my hand but not sure I am going to keep it because of cost even with insurance The trouble with walking just happened yesterday. First time FYI. I am a breast cancer survivor. Thank you.