Icy brain sensation when off methylation?

[Ninan]

When my B12 protocol doesn't work, I crash severely. When I do, and some time before, I have a cold, icy sensation in my brain. Mostly on the top/back and high up on the sides. I googeled it and it seems it could bu due to decreased blood flow/vasoconstriction? Someone associated it with B12 deficiency. Anyone who recognizes this feeling?

 

[Mrs Sowester]

I sometimes get a cold sensation as if someone has injected cold water into a vein in my neck that travels up into my brain. Is that similar to what you're describing?

 

[Ninan]

Not exactly. It never goes that far down.