With your thyroid and cortisol levels being fine, how are your nervous system symptoms? It may be related to that.
Just to be sure, they have checked your pituitary gland as well? There could possibly be an issue with that still.
My nervous system seems to be OK. That's never been a big symptom for me. I had an MRI of my adrenals and pituitary gland at the beginning of the year, and they were fine. (Before I had a diagnosis, my GP was ruling out tumors, MS, etc.).
I thought maybe blood sugar, but I've tried getting up and eating an orange, and it made no difference. I'm stumped.