Suggest Remedy For Severe Headaches

gender: female age: 24 yrs height: 5 feet 2 inches weight: 50 kgs suffered from heat stroke in 2002 i frequently have severe headaches at night in the back of my head. i feel as if someone is hitting me hard. i also feel dizzy and nauseatic at that time. this has been happening for the last 2 months or so. what are the causes of this pain and what are its remedies?