What Causes Bumps And Itching All Over The Body?

Hi! I get intermittent itch all over my body, (except my feet) which arises all of a sudden without much warning in one or many areas of the body and while it subsides, another starts in another area. I also sometimes feel that heat radiates out from my back and behind my ears. The pimples I get are generally mistook for mosquito bites and the itch is has almost the same irritation. What could this be?