We can't say, but it's always best to check out any new symptoms with your doctor before assuming it's anxiety. You need to know if it is a pulled muscle or not, you may be doing more damage by not taking it easy, and having a physically demanding job like you do would make one lean towards it being a muscle. But only a doctor can tell you this, and knowing for sure what it is will also ease your anxiety. Take care.
Hi!! Of course, I'm no doctor but I can tell you based on experience that it seems like anxiety could be behind this. Of course you want to see a doctor if it bothers you enough and persists. I know that when my anxiety gets really bad I have horrible sleep and that causes my back to get all out of whack. My chiropractor has told me before that problems in your back, like a pinched nerve, can wrap around to the front, so sometimes an adjustment helps me with that. Of course if you are having breathing issues, quitting smoking would help, but you know that. Breathing sensations like shortness of breath, or more like a feeling I'm not getting enough air to my own satisfaction often couple with my anxiety and then everything is down hill from there. It's easier said than done, but relax and take some over the counter tylenol perhaps, or if you take anything for anxiety. If it keeps making you that worried or uncomfortable then give the doc a call. Hope this helps some.