Random itching all over body ! i am not taking any medication ! no rashes....seems normal....but once i scratch i see rashes?

Dermatographism: Dermatographism means the ability to write on the skin. People with this form of chronic urticaria are sensitive to touch and pressure, as well as scratching. The areas of skin that are touched or scratched get a raised, red and itchy rash. While many people with chronic urticaria have features of dermatographism, people with true dermatographism have pressure as the trigger. Try Antihistamines.