I hope it goes away for you soon. For me, I would feel some chest tightness every once in a while early on when my I was in the midst of more severe symptoms, and doing breathing exercises focusing on slowing the breath helped to relax me enough and thus my breathing muscles. I like the 4-7-8 breathing method to help slow the breath, something that may help to relax those muscles and hopefully would reduce the feeling of tightness. Let me know how it goes and if it goes away.