I have been yawning excessively, what could this mean?

I am 12 and i have been yawning about 1-2 times every minute for the past month! And if i don't feel good (my head hurts, stomach hurts..etc.) then i yawn it goes away and i feel normal. then if i haven't yawned i feel really out of breath. could this be low oxygen levels to my head or what? I want to know if this could be bad..