Consider this...


It sounds to me like an example of referred pain from tight trapezius muscles. See below.

Google Image Result for https://www.researchgate.net/profile/Carel_Bron/publication/51450419/figure/fig1/AS:202521160228864@1425296215137/Referred-pain-patterns-red-from-the-upper-and-lower-trapezius-muscle-MTrPs-Xs.png

Referred pain means that a trigger point in one muscle can create pain in another area. For instance, when the muscle at the top of your shoulder (trapezius) has a trigger point it will refer pain up the back of your neck and head causing a headache.

These are stretches to overcome pain.

How to stretch the trapezius muscles properly! - YouTube


Even if this is not the exact cause it is likely to be a similar external muscular cause so a CT Scan is not really necessary.

I agree with Jo*mar, you really need to undergo work station analysis.