What Causes Bruise Like Dots From Foot To Upper Thighs?

Hi my 5 year old daughter has bruise like dots running up the back of her left leg and the top of her foot. This has never caused her any discomfort as a bruise would however it has started to creap up the back of her thigh and has been there since the end of november. After being referred for blood tests and coming back clear she has been referred to the hospital for further examination, do you have any ideas?