Trigger point injections for neck/shoulder knots and tightness?

My S has been dealing with frustrating neck and shoulder knots/tightness which cause him a variety of issues - nerve pain behind ear, classic tension headaches in back of head, neck stiffness, etc. After MANY doctor appointments, we are fairly certain this is all the result of his bruxism (teeth grinding) /TMD issues which keep his jaw muscles very tight. He does have some limited mouth opening although not to an extent which prevents eating.

A quick recap since January - he has had a brain MRI (normal), cervical MRI (normal), had PT, and been on several meds, including a muscle relaxers. He was also fitted for a custom night guard which he wears religiously. He has been off all meds since early March and has been doing very well until about 2.5 weeks ago.

The only thing that has changed is he has re-started weightlifting (P90X/shoulder workouts) which he had stopped back in the fall when all this started. Perhaps, that was the trigger that put his muscles back into spasm as his jaw/neck muscles are always tight anyway?

The oral surgeon wants him to take the muscle relaxers again which none of us are happy about. I have read that trigger point injections can be very effective in treating myofascial pain - which is what this sounds like although I am no doctor. I know they can be done with or without steroids and sound like a better alternative to more meds. He goes back to school in a month so I am feeling a bit desperate to get this under control again.

Any thoughts/experiences?

Have you explored trying a chiropractor and massage therapy (such as TMJ massage and lymphatic massage)? It sounds like his issues are ultimately physiological. I had chronic back pain for 25 years that was resolved this way within the last 2 years. It can sound hokey until it works. Trying will cause no harm and if it works…