I Have Had This Really Bad Pain That Goes From

I have had this really bad pain that goes from my hip all the way down my leg to the point I can barely walk or put pressure on it and the pain gets really bad in the evening .. When I lay down my whole leg just throbs and it's very painful to get up and try to walk ... So I'm wondering what is going on.. The pain had me in tears last night.. So I need hel figuring out what's going on