My neck isn't showing any obvious signs of injury (and the well-regarded neuro who examined me did not identify any neck issues) but I find that my neck and upper back can get a bit stiff, possibly from the relative inactivity during my recovery. For example, I haven't done much in the way of head/neck stretches b/c I don't like tilting my head all the way forward for any length of time.

I find hot showers helpful up to a point. I also went for a few cranial-sacral massage sessions a while back (for PCS generally, not for any neck issues). The sessions were somewhat soothing, but I didn't like some of the techniques (including one where the therapist seemed to put my skull in a kind of vise with her hands and wrists). I also found that the bumpy car ride there and back seemed to somewhat negate the benefit of the therapy.

Basically, I'm looking for gentle ways to keep my neck comfortable, loose, flexible, etc and to maintain good circulation in that area.

Of course, if there is a chance that I have an ongoing neck injury (it doesn't seem like it to me, as this seems like a minor and intermittent issue, but who knows - it took Sidney Crosby about a year to figure out that he had an injured neck), I would like to identify and treat it as well, but I'm not sure how to go about doing this. Would a reputable orthopaedic doctor be a good place to start? Maybe an osteopath?

Soft tissue damage/muscle spasms etc, can have lasting effects just as much as bone or joint damage.

Drs usually tend to think more in terms of bone/joint problems and not so much at the soft tissue part of things.

A good massage therapist, or possibly even a chiro that does PT type modalities like ultra sound, IF stim, low level laser etc should be of help.

If you want a MD then probably an osteopath or physiatrist (a rehab/sports med type dr).

Not my neck so much but I still have tightness and occasional spasms in my upper back, this 18 months post accident. I have deep tissue massage therapy about once a month, I also do slow stretching of the neck daily as a finish to a mindful meditation session (which I also find helpful).