I've been receiving hydroxocobalamin injections for a few months now, and am I'm noticing that I 'run out of steam' after about 8 weeks, not 12. I know this is commonly reported. But I also seem to be getting arrhythmia towards the end of the period, and then it disappears a couple of days after the injection. Is this common? Does the injection sometimes need a couple of days to take effect? Is it just a coincidence that I get arrhythmia when my B12 is getting low?