Ask HN: How to relieve psychosomatic back tension?

For the past two years I've been regularly feeling a kind of deep tension in a very specific part of my back, namely on the left side of my upper back, very close to the spine, around the height of the middle of the shoulder blade.

I know precisely when and how it started, and it seems to come back without any physical strain or bad sleeping, and then it dissipates just as easily a few days later, at times a few weeks. So I'm convinced this tension is psychosomatic. Not exactly sure what activates it, but it often happens in periods of stress and anxiety. And sometimes it disappears when I travel to another city/country.

Any tips from the HN community on how to remove that tension? I'm thinking special stretching, breathing, joint cracking, or other exercises/techniques...