I know that you have done breathing exercises before...but this one is really, really effective.
All of the symptoms you mentioned can be attributed to hyperventilation...something that we often do without even realizing it!
Here is my personal favorite...it is the only one that really works for me.
The Divided Breath:
Imagine your lungs as having 3 parts. The bottom third, the middle, and top third. On the inhale fill the bottom third first, then the middle and finally the third. Make sure that this is one continuous breath, but divided, with a slight pause in between each third. Hold the breath in for 3-5 seconds if possible. Exhale in reverse. First blow out the top third, then the middle, and finally the bottom third of your lungs until all air is expelled. (remember the pauses) Repeat several rounds for a toatal of about 10 minutes. Practicing this every day will not only give you control and structure to your breathing, it will strengthen and loosen the thoractic muscles, allowing better, more productive breathing, and relieving the chest tightnessHope you find it helpful as well
S.C.