What kind of Respiratory problem is this?

some random times of a day i'll feel like i can't breathe and i need to constantly yawn until i get a nice satisfiying breath..during these times it feels kind of like not enough air is going in my lungs...i was diagnosed with asthma but i really don't think that's what this is...it happen/ alot when i'm in bed and when i start to fall asleep, sometimes i jerk awake because i get scared that i'll stop breathing.