It is an inter-connected system… if you are low on iron or folate, then the body is not able to absorb / use B12 effectively either.
It sounds like you have other neurological symptoms, so I would go to your GP, and ask to have iron / folate / B12 deficiencies ruled out as a cause of your neurological symptoms (tinnitus and tingling / numb extremities).
GPs usually request ‘total B12’ (serum B12) blood test - but actually ‘active B12’ blood test is a much better measure of how much B12 you are able to access. If you are borderline, or in the ‘low normal’ range, and the GP refuses to start treatment - then you have a few options.
One of which is to seek a private consultation with an anaemia specialist (I saw one based in Cambridge who seems to be one of the few people who really understand B12 deficiency / iron anaemia). If you’re interested (and you have no joy with your GP), I can DM you his details (he is an NHS consultant, who has a private practice on the side). I don’t live near Cambridge, so travelled for the appoIntment.
With neurological symptoms, B12 injections (not tablets) are recommended. In the UK, The standard NHS treatment protocol is loading doses (B12 injections) every other day for two weeks, then a B12 injection every three months.
The healthunlocked B12 deficiency / pernicious anaemia forum also has lots and lots of super helpful people who can advise.
It is worth taking this seriously, as it is not called ‘pernicious’ anaemia for nothing - it can strip the protective coating from your nerves (including auditory nerves! = tinnitus), and can cause a huge amount of neurological symptoms - some of which have even been misdiagnosed as psychosis, and even dementia.
As a final note, I am not a medical professional - I have a functional B12 deficiency (meaning while I can get B12 into my blood, I have problems accessing it at a cellular level). I suspect functional B12 deficiencies are massively under-diagnosed… serum B12 blood tests won’t show a deficiency, it can only really be confirmed with a Methylmalonic Acid blood test, and a homocysteine blood test. GP’s can’t request these, they are only really requested within a hospital setting.
ps - I found my symptoms got much worse during menopause - so I suspect something changes in our ability to access B12 during these times.
Sorry for long post!