The letter to my GP ended like this:
"...her chronic neurological symptoms such as problems with memory, poor concentration, changes in mood and fatigue are well described in vitamin B12 deficiency though are relatively non-specific (for example they are also seen in primary headache syndromes such as chronic 'silent' migraine or chronic fatigue syndrome) .." although I showed him the diagnosis of Functional B12 Deficiency from St Thomas'.
However, he HAS requested an MRI of the brain to rule out a structural cause, and nerve conduction tests.
He suggested "some other medication could be trialled such as riboflavin or co-enzyme Q10 as these can be effective in chronic headache syndromes (and are thought to improve neuronal energy metabolism more generally) it is thus feasible they may improve some of her chronic neurological symptoms" .
I don't have headaches and have never complained of them. When I said this, he said that you can have this chronic headache syndrome without headaches. By this reckoning, It may be a long, long time (and continuous re-diagnoses, and treatments for conditions for which I don't have any symptoms that aren't "silent" !) before I get symptoms that are recognisable to the experts as belonging to B12... and it may well be that these ones are by that point irreversible.
I have a 2nd appointment with the haematologist on Wednesday - any advice on what to ask for or how to put an end to this guesswork ?