I have cousins that are 6' and over and they tend to slump, roll or hunch their shoulders.
Plus adding in your many yrs of computer work- made me wonder about the repetitive injury angle or TOS.

I was thinking that possibly your head /neck alignment might be forward of the body also {looking down at computer screen -or up if raised to high} which will cause stress to the c spine.
Causing changes and pain and muscle spasms.
Some with TOS have TMJ symptoms and c spine issues too.

Have you considered an expert chiropractor?