Hi Workaholic,

RSI can't usually be seen on tests like NCS, EMG or MRI so all these tests will come back normal.
The pain is likely due to nerve injury above the site of pain. Since you have pain in the elbows and ears the injury is probably in the neck. I think neck can also affect vision.
Did the doctors do imaging of the neck and excluded herniated disks or stenosis?

If so, you problems may be due to tight/spasming neck muscles which can be because of a poor posture and muscle imbalance related to excessive computer use.
If exercises made you feel better, it is because they engage different muscles and take the load of the overtaxed muscles in the neck.
Rest is helpful for the same reason: takes the load off the muscles.
Unfortunately, doing exercises while continuing computer work may not be sufficient.

I have many of the same symptoms you described which developed slowly over 20 years.
Headaches, ringing in ears, neck pain, pain behind eyes, shoulder pain, wrist and elbow pain.
I was doing PT and various exercises for years with no improvement.
A couple years ago my symptoms suddenly got worse and within a few months I was unable to work on the computer even for a short period without triggering bad pain which lasted for days.
Like you, I have knee pain which I think is also caused by nerve irritation.

What will probably be helpful in your case is to take a break from computer.
Like not touching it for 6-12 months and invest some serious effort into improving your posture. If you have a head forward posture common among computer users, it needs to be fixed.

In my case I am seeing some major improvements with reduced computer use and lots of exercise and stretching during the past year. I can now work on the computer for a few hours a day without triggering bad pain.
My knee pain is also better. A year ago I could not kneel or squat for any length of time without pain. I can squat all I want now. Still getting some pain after prolonged running though.

Check out the TOS forum posts, there is a lot of information there on exercises.