I'm not surprised he fell asleep on the train. I fell asleep riding in a cushy ride car and my neck was messed up for weeks. I had so much inflammation in the upper neck that I could not get my heart rate or blood pressure up for those two weeks. I could hardly get up out of a chair. The head slumped forward or two the side is killer on an injured neck.

I wonder if your chiro knows a gentle neck technique that is worthwhile. If he did, I would think he would have tried it long ago. Many chiros think they need to hear that pop. Some gentle traction with mobilization and gentle manipulation may be best. If he is not gifted at such a technique, you should consider finding someone who is. My PT was helpful for me.