i read your question. it sounds like you are having some kind of nerve dysfunction in your arm and face which is causing the pain and the inappropriate vasomotor response (flushing).
one diagnosis which comes to mind is Reflex sympathetic dystrophy (RSD)- a clinical syndrome of variable course and unknown cause characterized by pain, swelling, and vasomotor dysfunction of an extremity
if you haven't seen a neurologist, i would recommend that you do so- particularly one that is affiliated with a university- they have access to the most up to date equipment and technologies. they will also give you guidance as to how to manage the pain.
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