Suggest Treatment For Numb Knee And Damaged Nerve In The Lower Back

1 week ago I experienced low back pain that caused me not to be able to walk or stand without pain. I went to my Ortho Dr. They took xrays. Said I have nerve damage. I have to go back for a follow-up next week. Now I am experiencing numbness in my knee (I have had total knee replacement). Still have some pain but not as much. I also have experience my knee becoming weak causing me to almost fall. I have been doing the exercises they gave me to do. Could me walking/running everyday prior have caused this problem ? The pain was so bad, it woke me up from a deep sleep.