I had this happen! The neck was out of place. We x-rayed the elbows and the shoulder and finally the neck, almost six months this dog suffered.

The Vet recommended a chiropractor. We took the dog to a chiropractor and he did great after his adjustments. She tried to show me how to adjust him after a while and I threw him back out of place and couldn't adjust him. He is now well and older.

Just a thought that it could be something this simple.

It could also be pano, there are many things it could be including a strain. By asking everyone, you're going to get many answers.

If it continues, go see an orthopedic vet instead of lay people without names, degrees and who are throwing their opinions out there including me.

I hope it's growing pains too.

Any chance you know a good equine vet who could do an MRI for you? Might be something there that the X-rays aren't picking up?

Good luck, hope you find some answers soon!