My 15 year old granddaughter has been experiencing dizziness, headaches, stomach ache and heart palpitations for about a week, she has been to the DR who said stay out of the heat she went to the emergency room also and they said everything looked fine and to drink more water, she has been drinking a ton of water and it s been raining and cool here for the past few days, the dizzy spells she describes is close to fainting, I m very concerned, any ideas?