Itching and sneezing. Then whole body.

I don't know what is happening to me. All of the sudden when I my body gets little heat whole body starts itching and it feels like so many pins are piercing through my body. It makes me crazy for few seconds and after few seconds it goes away. While I laugh I feel itchy, when I het excited I feel itchy, when I do workout I feel itchy, when I go in sunlight I feel itchy. And in fact sometimes all the sudden when I am sleeping under that fan and if someone woke me up I start feeling itchy again. Also sometimes when itching starts immediately I get sneezing 2-3 times. I don't know what is wrong with me but It really makes me crazy for few seconds. I am tried of this. With a little amount of heat it starts. When I wear shoes with socks then also it start itching from leg then whole body.