I’ve had chronic B12 deficiency over the last twenty years. It started a few years after chronic pain diagnosis. I wonder if it was from the health condition or the medicines depleting my system. One of my most trusted doctors (very few) told me the B12 pills don’t work. Only the B12 injections or a sublingual B12 pill is effective. I’m not an expert or doctor. It’s hard to find B12 sublingual, only a few companies sell it. Vitamin D, magnesium & potassium deficiency is very common also. Ask a doctor to run magnesium blood work and they think you are crazy. Most people are magnesium deficient. Magnesium oil spray or body butter works as good as a pill. Even soaking in epsom salt & magnesium flakes will help. Epsom salt contains magnesium if you don’t have mag flakes the salt is sufficient. If you can’t get tub a foot soak will do.