Face began w/ heat rash & now hives on forehead & jaw. Gym 7 hrs wk. I shower right away at home. Wear clothes that wick but head sweats. 66yo f Tx?

Hives. Hives may be exercise or heat related and the facial rash could be due to an allergic reaction to something that comes in contact with your face. If rash or hives don't appear on the rest of your body, an allergy to food,etc doesn't seem likely. If symptoms persist an allergist is best qualified to evaluate and advise you. In the meantime try to identify any culprit substances that come in contact.