I'm a 14 year old cross-country runner who wakes up at 4:45 and goes to sleep around 10, I'm not necessarily worried but I would like to know what's going on and how to fix it. during classes I'll be fine, whenever I get up to walk to my next class though ill get very nauseous and ill get a headache, sometimes it gets to the point where I feel like I'm going to faint. I've also been very fatigued, after relaxing in one class I'll fall asleep and wake up near the end of class but I can't ever get my energy back after that. Ideas?
Oh and it will last until a minute or so after my next class has started