What Could Random Itchy Rashes On Body Suggest?

I have very itchy skin all of a sudden. the itchyness stops in one place then starts somewhere completly different. Sometimes my back then on one leg or both, then my arms stomach even my head. There is not much of a rash acompanied by the itchy skin but just some pink or redness then it goes away and starts someplace else today it roamed all over my body and was very uncomfortable.