What Causes Headache, Breathlessness And Fatigue While Playing?

I have lived in Utah my whole life, but since I went to Mammoth Lakes, CA I ve had a really hard time running, I ve had bad headaches and things that normally don t bother me, like walking up the stairs, playing in soccer games and running, leave me really out of breath and tired. Sometimes I ll just stand up and I will be light headed and dizzy and will have black dots on my eyes. I m really panicked because I have high school soccer tryouts in a week and I can t compete at the level I need to.