Been very tired lately?? Not able to sleep.?

I am very tired lately. I am a teenager. For the past 2 weeks, I can't go to sleep till like 12:00 to 2:00 am. I just can't fall asleep before then even if I am exhausted. I can go to sleep for like 30 minutes sometimes, but just small things will then wake me up and then i can't fall back asleep. I am not a light sleeper either, because my loud house alarm went off the other night and I slept through it. I also workout 4 to 6 times a week for 30 to 105 minutes. I usually am pretty energetic in my workouts, but for example last night in workout class I almost fell out. I am just so tired, but I can't sleep. I need to workout today,but I feel so fatigued. What could be wrong with me??