Which B bit levels? If it is B12 then read everything you can about it, follow up the testing, and read Mrs Doubtfire's thread on it here on NeuroTalk. Also check to see if you have low folate too. B12 problems can be reversed easily if caught early, less so if they cause damage. They can mimic a whole load of conditions, as well as be indicative of pernicious anaemia.

If not follow up on it anyway. Then there is time to consider PD. No-one really knows what very early PD is, because there is little data on it. Testing for PD is, with the exception of DatScan, by clinical observation. There is some evidence that possibly early PD is evidenced by loss of sense of smell, but this is not as yet definitive. It is also usually a diagnosis of exclusion of other conditions, which would mean checking out a whole load of conditions. From your description you have not yet run through the whole gamut.

It is miserable knowing something is not right with ones health, but not getting an answer. Good luck with finding one, and hope you do not have to join this club, though you are of course very welcome here.