I have had forward head posture for a couple of years. I assume this is not good for someone with a subtle neck injury. FHP is actually the main thing my PT has worked on. I have also had a very stiff neck the last couple of weeks which she has also helped a bit with: trigger point release, massage etc. She has given me a lot of exercises to do at home which I have been hesitant of doing, mostly because of my low tolerance for physical activity. I have weak muscle on the side of the neck and between the shoulder blades.

Would it be considered as pushing for range of motion to do exercises where I have to tuck my chin in and push my head further back than it usually is?
In other words: Could it be bad to try to fix the FHP while recovering from the neck injury?

A couple of days ago something happened that reinforced the idea that pushing my head further back than its neutral position could be bad for my neck.

I was lying in bed, and I tucked my chin in (probably further than what would be considered neutral position for someone without FHP). As I did, I heard a loud crackling sound. I have heard crackling sounds from my neck before, but this was unusually loud. The following minute, the sensation in my body gradually decreased to previous levels. My head also got foggy, and a feeling like my eyes have low frame rate (which I think others refer to as slow-motion feeling) reappeared. And I should also mention I have noticed that when the lack of sensation symptom is at its worst, my face is less firm.

It might just be me looking too much into it, but the curve of my neck feels different now. I also feel more uncomfortable lying down. Now I can't sleep on my left side either, although I'm not sure this started after this recent occurrence or before that.

You told someone on here hat he should abstain form doing yes and no movements at the same time. He wrote he had, I can't remember where but, an injury not in the upper neck.
It feels like my neck stiffens when I do a combined yes and no movement. I noticed this before the neck-crackling-occurrence. I'm not entirely sure I can trust my mind on this since I noticed it after I read about it.And I haven't done it on purpose yet as I'm afraid to do so.

Should I try to do this movement more to see if this is a problem. Why is this particular movement bad and what cervical injury is it bad for?

Tomorrow, I'm going to a chiropractist which is quite popular and has a good reputation. But he is not a neck specialist as far as I know.

Should I let him touch my neck or is it too risky?
My lower back also hurt, so I think I might benefit from going either way.

Is there any way at all to get a proper diagnosis of subtle neck injuries?

Should I ask for another MR scan?

There is some good news. My sensitivity to bumps and jolts has become quite a bit better over the past month. It could be thanks to the supplements and a not so strict anti-inflammatory diet.
But when I experience a big enough jolt, for example riding over a big bump, I feel it in my teeth. It's the same feeling I had for a day after my PT pressed my head very hard towards my spine, and it wasn't like this before.

What could this be?