I am 16 years old. I was a long distance runner athlete and vegetarian. I was training to run a half marathon before my health declined.  For the past 2 months I started having headaches and other symptoms. At first it was just the headaches everyday, they are sharp and pounding and I can barely function. Then I started getting weak, so weak as if I haven't eaten anything but I eat. I lost 18 LBS/ 10 Kilos unintentionally (after i stopped running). The headaches used to start in the middle of the day, now they start in the morning when I wake up. I'm shortness of breath all the time, like me, an athlete can barely walk up the stairs now. I can't do anything physical without feeling horrible and out of breath and weak. My hands and feet are cold all the time. I can't even make it through an entire school day without going home because my headaches are so bad. I'm also fatique, everyday. None of my symptoms stop no matter how much protein and sleep I get. I've been to the ER 3 times, and the last time I went they gave me a CT scan,so it crosses out any tumors and anything neurological. Can please give some advice of what is wrong with me???

My symptoms in a nutshell are:

* Sevre headaches daily. * Weakness daily.* Fatigue daily * Coldness in hands/feet daily *Shortness in breath daily