What Causes The Itching And Rashes On My Hands And Legs?

hi sir, i am 24yr old guy, my height is 5'-9", and my weight is 68Kgs. Two weeks before i started going to gym for bodybuilding,and i am using "Endura Mass" health drink powder for gaining weight. The problem now i am facing is, since two days onwards during early moring hours i am feeling that there is no proper blood circulation happening in my hands and legs and i am feeling itching sensation . And if i am scratching my hands and legs due to itching, then rashes are appearing on them and slowly after some 1hr it is becoming normal. I don't know what is happening to me please suggest me what to do, and which specialized doctor to consult.