I have the neck, shoulder, arm, palm and last two fingers situation too - I have been in extreme pain for several months with this and after a steroid injection into the shoulder I now feel a little relief. However, I have had Physiotherapy, blood tests, x-rays, MRI and am now awaiting a nerve conduction test. I was informed by an orthopoedic specialist that I have cervical spondylitis but he did not think this was directly causing the shoulder problem. He thinks it is definitely neurological and that it will probably require an operation to release the trapped nerve. However, nothing can be done till I see the neurologist.
I sympathise with you and the despair you feel. I imiagine that you, like me, become sensitive to the looks that pass between friends when they hear that you are not well again and you get to the point where you don't want to talk about it any more. But this forum can help as you will find many sympathetic people here.
One thing occured to me - you seem to have a huge remit. Can you delegate some of your load to others? That, combined with the fact that you are seriously sleep deprived and exhausted, could certainly contribute to some of the muscular pain you have been experiencing. Take the meds every night - take the codeine early enough not to impact on your working day. Ask your doctor about Amitriptylene too, as that , in small doses taken at night, will relax your muscles, solve the restless leg syndrome and encourage restful sleep.