How To Treat Skin Irritation Causing Bumps On My Body?

hello Doctor. I am having a skin irritation from the past 2 weeks .. its itches severly, has red spots , its dry and feels like bumps all over my skin. its on my hand , legs, and mostly all over my body.. the affected areas becomes hot later on ( after scratching ). i dont know what is the cause but i am having loads of problm with it ... please help me !!!