What Causes Mild Burning Sensation In Legs Spreading To Inside Thigh?

3 days ago I started to feel a burning sensation on a patch of my leg right above my knee. Since then, this mild burning is occuring in other patches around the area, and is made better by standing up or moving. It has spread up to my inside thigh. Sometimes it is slightly painful to touch, or there is a pins and needles feeling. It occurs for about 40% of my day. I am around 20, and no, I am not sexually active.