What Causes Red Itchy Spots In Arms, Legs And Body?

I am a elementary teacher and I caught a flu from my students. I was sick but I did not take any medicine. After I got better, I body start to break out red itchy spots on my arms, legs, body, but not on face. These red spots were not blisters, but they do form scabs, and leave a white mark afterward, Someone told me I should expose these areas under the sun then the white spots will return to my skin color. I have gotten better but every now and then these spots come back, but not as many as the first time when my whole body was cover with them