Thank you for your suggestion, WC. Many years ago I was referred by a pdoc to a kindly neurologist who ordered an EEG based on my symptom of derealization. Nothing showed up, but the tech told me that EEG's are not entirely reliable unless there's active seizure activity happening during the test. Whatever that meant.

Had an MRI just a few years ago; looked normal. At that time was referred to a neurologist - the meanest, rudest doctor I have ever seen. He barked at me that as long as I'm on Klonopin there's nothing he could do for me because Klonopin obscures EEG results . There was no getting anywhere with him.
My current pdoc agreed with me that there might be something neurological going on...your question reminds me that I need to question her further. Maybe she'll give me a referral. I'm so used to this way of "seeing the world" that I tend to just accept it. But it would sure be nice not to have to live with this weird sensation 24/7.