What to do if i am 19, been to er for inability to obtain full breathe, 100% o2 clear lungs and airway?

Anxiety?: I'm not an md but if the er cleared you, perhaps you are anxious about something going on in your life. Are you in college? Working? Starting on a new adventure in life? Under a lot of stress? All these can make one feel as if they can't catch a breath. Try yawning. Sounds silly, but it's a great way to feel the breath through your entire body. Try exercising and/or using relaxation techniques.