Hello dear friend,
I can sense that you are getting anxious about your
vitamin B12 levels,but 278 is not low but within normal range(towards lower side but still above the defined limit for low levels as anything above 200 is normal).Even if low,it would have caused symptoms related to anemia(usually pallor,
fatigue,palpitations,breathlessness) or neurological deficits like impaired joint position,inco-ordination of body parts,limb weakness or stiff legs.In my clinical experience of a few years,I have not encountered patients of B12 deficiency causing prominent leg pains or people getting episodes of
dizziness due to vitamin B12 deficiency(dizziness although may be a part of anemia sometimes).I would suggest you to go to a
neurologist and he will,after analysing your history and examination,will tell you about the possible causes of dizziness in your case,which can be several otherwise, like
postural hypotension,positional dizziness,some ear pathology and a few others.I hope it helps you.