I woke up with a bruise on the inner side of both knees. One looks like a bruised vein or an artery . It is about 5 inches long and about quarter of an inch thick, from the edge of my kneecap on the inner side of my knee, diagonally heading down tapering towards my left calf muscle . It is quite a sharp and painful pain no matter what way I am sitting, lying down or standing, the pain isn t going away. On my right knee, in exactly the same position as on my left knee, there is a small dark purple/black bruise about quarter of an inch wide, and the pain is identical to the left knee. I have not bumped, injured or done anything to hurt my knees. The only other thing is my left leg from the knee down, and my whole left foot was a bit swollen and tight feeling, what has caused this? I would be most grateful for your reply.