Why do i itch when i take hot showers, sweat and before runs i have to take zertic. what's wrong?

Hives: You probably have cholinergic pruritus. Regardless when we get hot our bodies release more histamine and other chemicals causing itching and redness.

Aquagenic Pruritus: Aquagenic pruritus is a skin disease that causes intense itching when the skin comes into contact with moisture. The disease is easily diagnosed because of its unique symptoms. The exact cause is unknown, but the chances of developing aquagenic pruritus increase if one has polycythemia. Though non-life threatening, the condition can greatly decrease one's quality of life. There is no cure.