'very nervous and full of anxiety '

These things will cause any of us to tense up and not breath fully- all bad for health , we need that oxygen and to breath out the bad air.
plus you hold the tension in the muscles too and that makes comfort even harder to achieve.

look for some videos on Google or you tube about relaxation and relaxing sounds- to help you destress.

If those are not very helpful -and since you have a chronic pain condition already -maybe ask dr about anti depressant or anxiety meds???
Some of those AD's work with pain meds to make them more effective.