What Causes Tingling Pain On The Back Of My Knees And Calf Muscles?

Sometimes I get a tingling pain in the back of my knees ( usually both at the same time) that runs down the outsides of my calf muscles! It happens when I am standing and try to sit down is hard! It lasts only for a short time and I have been rubbing a muscle pain crème or icy/hot on it! What causes this and it doesn't happen all the time! I never know when it will flair up!