My son has suddenly developed some kind of a rash on his left leg. It is on the front of the calf - two circular reddened areas about the size of a dime with a couple of tiny red spots nearby. Around the back of the calf are 3 small red areas now. He is not scratching the areas. There are no blisters. They don t look infected - but are red with some purple color. The small areas have increased in number by 2 today but the larger areas have not changed in size. What could this be?