I Have Pain Behind The Back Of My Knees And

I have pain behind the back of my knees and on the right side I have a pain that radiates down to my toes. When I wear even comfortable shoes, the ball of my foot goes numb and I do not get reliewf until I take off shoe and twiggle my toes.
I need to know what I can do to get relief or who to go to see for medical help.