Not to be rude, but: why? Your B12 level was dangerously low, and as you probably know, it is vital for many many processes in the body.

Once a low level starts to do damage, it is not just a case of taking a couple of injections to make it go away. It can take months and even years before there is noticeable improvement after supplementation, and there might be, I'm sad to say, lasting damage.

As Mrs. D already said: the protocol of one injection a month is a very very bad one. Even assuming that the injections are hydroxocobalamin, and not the pretty "bad quality" cyanocobalamin, it is:

a) not nearly regular enough
b) pointless if you have a problem with methylation

The protocol used to be to start with 4 injections in 10 days, then 2 injections a week until you notice improvement, at which point you can go to once a week and then once a month (which is maintenance). But again, oral methylcobalamin is cheaper and more effective, and I can say this with quite a bit of confidence having tried both methods.

BTW Mrs. D, I keep forgetting to mention: even if you do not have the MTHFR genetic error, things like smoking can cause the same methylation problem, but I guess that's half off topic.

To Ouchiefeet again (funny name though! ): please consider taking the oral methylcobalamin B12 (5mg/day). It is safe, it is cheap, it is convenient, it works.

I know docs do their best and won't intentionally harm, but sometimes they do anger me a bit.

Anyway, do not lose hope, there are still many things to try, including having a good look at your diet. I have likened the pain to "the worst toot ache" myself in the past, but you will find ways out of that hell. But it is really really important to get those B12 levels up (for us it means: > 1000); even if it will not ease the pain, it will prevent further damage.