It sounds like you may be hyperventilating from anxiety. I had this problem pretty severely when I was a kid. My mom would get me a paper bad to breath in and out in. Something about breathing in the already expelled air from your lungs helps. Sounds strange I know but really give it a try! Also I have to agree with the possibility of asthma. It could very well be adult onset asthma. I would ask your GP about it and get a PFT to test your ability of breathing deeply. I hope you find a solution soon, I know how scary it is when you feel like you can't breathe!

Sent from my iPhone using Tapatalk