Breathing heavily

Sarah • momma to Kayli 8/5/18 and Alayna 10/9/20 21

I'm a FTM, so extremely worried about every little thing. So, my daughter breaths heavy. And by heavy I mean heavy heavy. Sounds like she is walking up stairs every time she breathes. Scares me to death! Took her to Doctor and they checked her oxygen levels and listened to her heart and lungs and everything was perfect and she doesn't even have a stuffy nose! I'm at a loss as to what is wrong