itching can b of many reasons.from your question i understand that it is an acute one(recently started).It may b due to some allergy (the most common reason) of cold ,dust,pollen,medicines etc,or if u hav a history of hepatitis;incresed bilirubin in blood can cause itching.As u hav described it is generelised itching,nothing else can cme.if u write more symptoms i can help u more.