I'm on weekly injections that I give to myself. It's convenient because I can fit them in around my schedule, but it also means that's its up to me to remember to do them. I'm usually pretty on top of it and, consequently, I usually don't have my symptoms return between injections.
Yesterday was an exception to the rule. I was more active than usual over the weekend and it just flattened me. Somehow, while trying to recover from doing too much, I also forgot to take my B12. When I woke up this morning, my tongue was burning. Fortunately I was able to quickly recognize that as a low B12 symptom and realize that I had forgotten my shot.
I decided to post about it because it's the kind of pitfall that can happen if you get too complacent (and you are in a similar situation to mine where you are self-treating).