I get this same feeling with anxiety. I feel like my chest is tight and that I cannot take a deep breath. If I dont have this.....I have nausea. It is horrible and I can understand exactly how you feel.
I use relaxation techniques when i get anxiety and I will post some sites at the bottom of my text that explain relaxation and what techniques are good to use.
I also found that it helped me to actually understand more about anxiety. I used to panic more when I had anxiety and worry that my heart was beating too fast, the anxiety wouldnt go etc etc. I ended up getting anxious about being anxious.
In hospital I was taught about anxiety and that it would go away. Anxiety and panic eventually reaches a peak and cant get any worse so comes back down again. It cant hurt us and cant last forever.
anxiety is adrenaline and andrenaline is just a hormone. It cant hurt you and will go away eventually. It will reach its peak and start to disappear.
I find distraction helps and tend to draw, paint, listen to music etc when i feel it coming on. remember to breathe normally too, it would over breathe and this didnt help me at all.
Hope the sites are useful and hope i havent rambled on too much!!!!!