Inhaling deeply, holding for few seconds and exhaling for few more seconds helps to release pain. What we breath should be peace and what we breath out tension.
While breathing in and out, we must focus on breathing only. Have a peaceful background music and practice deep breathing (simple) technique.
As you get used to breathing technique try moving to advanced breathing technique of pranayama.
By deep breathing you will send fresh oxygen to every part of the body including brain. Brain receives the fresh oxygen and sends signal for muscle to relax.
Deep breathing is good for chronic pain and muscle pain relief..