OMG!!!! My nails looks just like this!!!!!! I'm going to run out and get some B12!!!!!
One indication that you might be deficient is the appearance of lines or ridges on your fingernails and/or the disappearance of the moons at the bottoms of your fingernails.
Methylcobalamin is the bioactive form, so look on your label to make sure you have that form of B12. Also, watch your peripheral neuropathy start to ease with B12, it is nerve food!