After running(exercise) i break out in hives. today it was only 4 bumps but its been all over my body once. only has happened 3 times not every time?

See an allergist: What you have is exercise-induced urticaria. It remain as urticaria only, but can develop into a more serious reaction. Rarely, it is caused by allergy to a food that you eat AND exercise within 2 hours from eating to suffer the reaction. In the meantime don't eat for 2 hours before you run and take an antihistamine such as fexofenadine 180mg 30 minutes before you run. See an allergist ASAP.

Cholinergic: This is called cholinergic urticaria which occurs when the body starts to cool down after a rise in core body temperature. It is a benign condition and usually can be controlled by taking an antihistamine about 1-2 hrs prior to activities which increase the core body temperature such as exercise.