Well a dr usually need to rx the PT , so they should specify what areas and why etc..

If you get a highly skilled PT they can also do evaluations to pinpoint what & where the pain/sx are coming from. If the dr hasn't done any hands on checking them they often pass that on for PT to do. and they usually have the head PT do the evals.
In the past for my RSI's, I did have a rookie looking in his book , so dr got me out of that place fast..

My dad has DDD with most discs gone luckily he has minor discomfort .

PT can also do ultrasound, stim and massage , which is best , to resolve some pain before they start with any stretching or weight/strengthening..

At any time if you feel much worse with PT tell dr so that is documented and a change of focus can be addressed