I agree with Larry.
If you take a look at previous posts, you'll see many, many of them are breathing-related.
I experience/d this as well.
Sometimes when I'm anxious I'll feel that way, and being aware of my breath, in the moment, conscious-breathing, helps me to realize I'm actually breathing very shallow, not utilizing my full lung capacity. This, in turn, causes hyper-ventilation, which also starts to muck about with O2/CO2 exchange, and voila,...it exacerbates things more.
So it is a cycle. Grabbing hold when you start to notice will help, don't just suffer along until it's driving you bonkers.
S.C. has awesome resources...they really do work!
M.