Back down to 4mg for the past 4 weeks and nothing has changed.
I had an initial consultation with a neurologist this morning as the latest attempt to get to the bottom of my chronic fatigue and shaking/sweating/nausea episodes. He confirmed there was no sign of neurological problems, which was reassuring but not unexpected. From a steroids point of view, his explanations were much clearer than my rheumy's.
First, he said that it was unlikely that my episodes were vagal attacks, as he would expect them to be accompanied by low BP and bradycardia - whereas they are normotensive and tachycardic. Second, he agreed with my rheumy that a disturbed adrenal system was not obviously implicated. This is because the episodes peaked while I was still on a higher-than-physiological dose of steroids and because the full body scans I'd had showed no adrenal tumours.
The conclusion was that for now, he could only suggest further attempts to improve sleep "architecture". But his suggestions were precisely opposite to my rheumys - to cut down the amitriptyline and not to start the gabapentine he prescribed. Instead, SSRIs might help reduce dream sleep in favour of increased deep sleep. So it was good to have been checked out, but I am no closer to resolving things. Endocrinology is next!