Hi CW.,
If this is something that comes and goes with your anxiety, and you are in otherwise good health and have been recently been see by a doctor (check up withing the last 6 months) then you can most likely assume this is an anxiety symptom.
I am guessing that you don't already suffer with asthma, or you would have mentioned it. You have not been sick lately with a cold/flu/cough have you?
Those are the only other possibilities that you migh want to consider having checked out...asthma or possible bronchitis.
Otherwise, you can probably get some relief from breathing and relaxation exercises.
We have some good ones in our Resources...but here is my favorite breathing technique. It's the only one that I ever felt really helped 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 tightness!
I hope that you feel better soon!
S.C.