10 years later I have not fully recovered. Doctors couldn't help (or see anything wrong on MRI), but said a lifetime of sitting in front of a screen 8 to 12 hours a day was probably the culprit. Solution was, unfortunately, to quit working. I'm typing this sideways laying down on a couch. If your neck starts to act funny, give it a rest!
(Building some contraption with PVC pipes as in this article had not occurred to me, but it seems like it would just lead to other muscles being overused, instead, with new injury somewhere else eventually)