Glad to help. Just remember that despite all the fancy sounding tests and big words we actually know very little about the brain and how it really works.

In his books Sacks (who is actually a neuropsychologist, not a neurologist my bad) usually just flags up these interesting symptoms, sometimes talks about ways in which they were mitigated, cured or went away of their own accord, but very rarely can he explain exactly why they occur or what tests might find evidence for them in a 'this part of the brain is damaged, therefore this has happened' type way.

The brain is just too complex, and every thought, memory, action or perception tends to take place in many different parts of the brain at the same time. I've heard it said that if the human brain was simple enough for us to understand, we would be too stupid to understand it.

So it's not unusual that such a weird symptom as this won't show up on tests - however it is documented that such things happen and there are people out there who will work with you on it, if you can find them. Good luck!