judging by the picture that you have posted, you certainly have some results to show for the almost daily weight workouts. I am sure you are very experienced in lifting weights.
Upper traps often jump at the opportunity to help when they are not wanted, and I suspect that you may have engaged them without being aware of it. I often see it in clients, and it takes an effort to bring this to conscious awareness.
Since you often sit in front of the computer and driving a car, you also need to be vigilant about your body position there. Particularly hours on the computer can create a head forward position which causes muscles of the upper back to tighten up.
Since you do not have a profile, I did not see where you are located. If you are in the US, I would suggest a dual approach with possibly lifting modifications in addition to the use of the MELT method. Since I am a MELT instructor, I can vouch for the effectiveness in helping with upper back release. Alternatively, you can look at myofascial self-release techniques using a foam roller and/or a Theracane. Here is a link to what this looks like http://www.amazon.com/dp/B0007YZ1BM/?tag=googhydr-20&hvadid=2246542511&h….
I wish you good luck and hope that you will get out of pain.
I agree, esp on the myofascial release techniques. In addition to the foam roller and
Theracane, consider a lacrosse ball. Small portable and can really get into the shoulder blade region.
A book that offers some movement beyond stretching is “Original Strength” . Lots in there to open the chest and restore posture.