Aw, I really feel for you - I've been experiencing a lot of anxiety this past few months and I know just how desperate it can feel
I'd say 'sit with the anxiety', but I know how friggin' difficult that can be when you feel like you're being overwhelmed; it might be more useful for you to do some chest-opening exercises, to stretch out the area, release some of the tension, and get the blood flowing a little better -
here's a link that provides some good chest-opening exercises.
You might also find it useful to try a breathing technique - there's one called the
4-7-8 technique that I've found useful, or else you could try simply breathing slowly and deeply in through your nose, pushing your stomach right out (the abdomen is the biggest nerve centre in the human body, apparently, and we can store a lot of tension there), and then out through your mouth. You might experience quite a bit of discomfort, but that's just the tension releasing, so stick with it and you'll feel more relaxed in time.
Hope that helps, and hopefully the anxiety lessens in time