Be sure to do a little warm up run and then stretch before you go on the main run. That was first thing I was told in Cross Country. Secondly, you build your way up. Start with slow ammounts of running and increse the distance every two days or even a week in your case. This may also have to do with how you are breathing. Properly would be in through the nose out through the mouth, it is hard at first but it really will make a difference. This breathing should be deep long breaths to prevent future cramping. As for getting tired so quickly what you need to do is check up on your running form. Wider strides will contribute to getting less tired, but not too big of a stride! (your not lunging or anything haha). It's all in your arms. ARMS ARMS ARMS! Pump your arms (swing front to back with your arms bent at 90 degree angle. your hand should practicaly be toughing your ear when in the front, and go far back when well back). hope this helps! Really helped during Cross Country this year. Good luck! Remember, takes a little time to get proper form. Sorry to make this so long there is just so much info. Also, one last thing. Pay attention on how you land on your foot. If it's a short distance and you are sprinting be on your toes and ball of your foot. While if a long distance that can cause shin splints so stick with heel to toe.
i'm a freshman but running cross country since 7th grade. and first year of indoor track (: