I have been using source Naturals B12 Dibencozide to add my Adenosylcolbalamin in my regimen, and It is slightly different than when I bought it in November last year (lasted til' late March). The same brand , but different taste and size, so I 'm not sure whats going on there. I get great results normally form using this version of B12, as my endurance increases. However, this current incarnation seems to be having a very reduced effect. I am discouraged. anyone else notice this problem?