Kind of hard to breathe since I woke up?

I'm 15 and I woke up with king of a "deflated" feeling in my chest. It's been about two hours and it still hasn't passed away. What might be the cause of this? I don't have asthma, I'm not overweight, and I don't have any health problems. I haven't done anything new recently; although I did sleep on a different bed tonight. Any ideas? When will this feeling go away?