If this is a new symptom, you need to let your doctor know so other causes other than anxiety can be ruled out. I only know of the deep breathing exercises, but stay with us as others offer advice and their experiences. I'm sure this has got to be very frightening, and hopefully others can give you some advice. Take care...
Breathing exercises used to make me feel a lot worse. A lot more aware of my breathing. Used to screw me up big time. The whole idea is to take you mind off the breathing. Inward thinking. That is what we are doing. We are noticing it more and we are focusing on it and making it worse. Got anything you like doing? I simply use an MP3 player and don't even think about how I breath now. Distracting the thought pattern is what you need to do. Just find that something that works for you. Mammo's famous elastic band trick might work too. Surprised she didn't mention that one. I will leave that to her. But anything to stop you focusing on your breathing. That's the trick. Takes a bit of time. Like everything else it is all about learning.
breathing exercises make me worse, i feel more suffocated, i just breath normal and ignore it, sounds daft but works, the more you ignore it the less you notice it