When I wake up, my heart normally beats unusually fast, and I get short of breath. I get dizzy when I stand or sit up, and am normally weak to the point where I don't want to move. Other times, I can't even feel it beating. I'm 16. I used to be a cross country runner and sprinter. I'm always tired, but I can never ever sleep. I've been diagnosed with Severe Depression, Anemia, ADD, and Insomnia, but they still can't figure it out. Any theories?