I'm 15 years old and during the summer I am very active. The end of this past summer I moved with my mom and I noticed changes in my body for awhile as my diet and home life changed and everything went back to normal. But this past month I've started noticing bad headaches and if I get up to do just about anything my heart rate increases very high, I get light headed, very hot, and sweat. Even just by walking around. I always keep myself hydrated and for the most part eat very healthy. What's wrong?