I too have had shoulder pain on the right side only, for around 4 years now. It spreads down my rib cage/back, down my right arm to my elbow, now the past year my right hip hurts alot and get shooting pains down leg. I hear a cracking/crunching sound at the base of my skull. Sometimes my right hand feels weak but not always. I haven't had many tests, my doctor thinks its all in my head ! I did have a chest x ray and ct scan of the back of my head for other issues and both came back clear. I am quite hypermobile, my posture is slightly out and I have endometriosis, don't know if these contribute/cause it. I now have anxiety too as you spend every day worrying what is wrong with you and feeling constant pain!
It is impossible to give you an answer as to why your shoulder still hurts.
It could be that removing the compression on the nerve root was too late, with damage already occurring, ie, demyelination at the neural foramen. Or it could be that in 4-1/2 years, you've developed a chronic pain syndrome.
Endometriosis, while seemingly unrelated, could also be contributing to a chronic pain disease. Anxiety would follow your history, with so many doctors, so much advice, no doubt some conflicting, and of course, intractable pain.
Often a pain syndrome has multiple parts. Cervical disease for instance, may produce pain from the degenerative disc itself, from pressure on nerve roots, from facet joint hypertrophy, and from muscles strained beyond their natural resting position when disc disease leads to loss of normal curvature. Multi-modal treatment is often more effective against pain for this reason.
While you have already visited a slew of doctors, I wonder if you've seen a board certified interventional spine and pain specialist? If a majority of your neck and shoulder pain is a result of facet joint hypertrophy, interventional pain procedures may help in reducing pain by 50% or more, as they have in my case.