[matwood]

You found what causes a lot of chronic pain - muscle strength imbalances. Many times the pain and the imbalance are not intuitive, but a PT can give simple exercises to fix the imbalance and the pain goes away.

Posture can also be helped with muscle strengthening. Years ago a PT gave me a ton of exercises to combat sitting at a desk all day. I still do them at the end of my usual workouts.