Hi Andrew, thanks for your post. The first thing that strikes me is you collective symptoms of fatigue etc. This might well indicate a physiological system that is overloaded/over stressed and the result of this is that the precking order for the bodies normal repair is upset. By that I mean the body will repair essential things first and often the connective tissue system is pushed down the queue. This means that normal repair after activity does not happen and we can get persistant soft tissue pain and discomfort. I battled with a neck for 18 months and tried everything I knew to fix it. No result at all. Then I talked with my osteopath colleague who was also a naturopath and applied kinesiologist. She assessed me and determined that I had some intollerances in my system which we then addressed with some dietary changes. In 10 days my pain was gone and I had not had any manual treatment at all.
A fracture scaphoid is often a persistantly painful condition. You need to consider how it was broken, what else was sprained/strained/torn in the process (i.e. ligaments), what is therefore now slightly unstable, and if the result is a non-normal tracking of the wrist. This is most likely and a job like window cleaning would perhaps not be the most recommended! That aside the scaphoid could also not be the issue and it is more one of longterm overuse and gradual soft tissue degradation, eventually resulting in pain. Rest will provide only short term respite if the connective tissue repair system is not doing its job.
I would lay off the exercises myself when things are painful. It is not likely that you need specific ulnar nerve stretches at the wrist but it could be indicated if someone can assess your neck, especially the cervicothoracic junction (where the neck attaches to the rib cage). Releasing this area (in fact the entire thoracic spine) is important to reduce any overuse and blocking of the neck vertebrae (where the ulnar nerve originates).
In terms of assessment you would only want a skilled hand therapist looking at you, maybe one with an interest in musicians (who often have persistanly problematic overuse injuries). If you are open minded have an assessment from an applied kinesiologist with a dietary view on any possible contributing factors in the issue. An MRI has already shown to be clear so I don't think it's of much use unless it is done with a contrast medium (called an arthrogram). A bone scan would be if you are more worried about the pain eminating from the scaphoid itself.
And as your job is your job, ask your treating therapist for the appropriate wrist support to wear when window cleaning. There are also specific surgical options for an instable TFCC (often seen in tennis players and gymnasts) which you could discuss with a hand surgeon if persistant TFCC is considered a major contributing factor.
I hope this helps a little with some new ideas.
regards