I don't know if this is anything to even worry about, but its been happening frequently enough to see a pattern. My 2 year old will be walking around and suddenly start crying that her neck hurts. Its always on the left side up near her head. I'm not sure if she is just twisting it funny, and kinking it? It happens every couple days, sometimes two or three days in a row. Not usually more than once a day. So its not really often, its just weird that its always that same side, and its not that she is bumping it or anything.
So for peace of mind, this is nothing to worry about, right?