Hives for 4 months on and off. No allergies as already tested. Hives get severe right before period time. But decrease the third day of period.?

Hives. With chronic hives, a cause is found in only about 5 percent of the cases. Causes of recurrent hives can be exercise, stress, cold and heat exposure, and anxiety. Your hives, maybe likely to hormonal changes.
Hives with period. Sounds like catamenial urticaria related to the hormonal changes in your cycle. Your treatment might be aided by discussing with an alelrgist and your gynecologist.