I have been supplementing with sublingual b12. I have managed to raise my levels from 250 to 2000. Had bloods drawn a week ago and doc has phoned very concerned at the high level. The problem is i feel so much better with my numbers high. Before supplementing i had problems with frequent urination which completly vanished after supplementing. my question is why do i need my levels so high to feel well and why do my symptoms reappear when i stop for a few days?.