I too am a developer who suffers from anxiety and panic attacks. There have been times when I feel constantly locked in a 'fight or flight' mode.
After trying many things to relax and cut out as much stress as possible, I finally found that trigger point therapy helps to resolve the issue. It turns out that years of sitting at a desk causes your chest muscles to become tight over time, and when that happens your back and shoulders work harder. Add in stress which causes muscle tension and you end up with chronic trigger points, also known as knots.
You can read up on it, but depending on which trigger points you have activated they can cause a range of symptoms from pain to anxiety. If you treat the trigger points to release them (which might take a while if you're like me), you'll feel really good.