Get some professional "hands on" phys therapy for the neck & muscle pain, you could have trigger points in the muscles, and the trigger points need to be resolved before any stretching will help the muscle tension..
Trigger points can refer pain & other symptoms to other areas - eyes/vision, headaches, and more.

Trigger point information {TrPs} for short


If PT doesn't mention or check for TrPS, mention it , if they don't seem to know about them, find a better PT..as with anything , there are good & not so good providers..don't waste time or money on poor care providers..

You might consider changing from a pediatrician to a Doctors of Osteopathic Medicine, or DO.. What is a DO? | American Osteopathic Association