Suggest Remedy For Pain In The Knee And Numbness

Hi I have recently joined a gym and have been using the treadmill. the pain started last week in my left knee, the pain in quite painful and i walked with a limp for a few days. it seems to be healing as i am walking better now but i now have a dull pain on the knee and a pins and needles/numbness in my leg. Is this something to worry about? Thank you.