There is not enough B12 in most B Complex supplements to correct a deficiency (amount needs to be 1000mcg or greater daily for a while, and you may need to find a different form other than cyanocobolamin); also, if a complex set of variables aren't just right, the B12 won't be able to cross from the gastrointestinal tract into the bloodstream where it can be processed by the liver. And there are other issues in the liver itself that may further cause problems with conversion, utilization, and/or storage of B12.
So try a high potency B12 supplement - sublingual ones are usually better than pills that are swallowed, has to do with how well the mucus membrane in the mouth can absorb the B12 vs. once it is further down in the gut.
Chronic Lyme Disease, Chronic Bartonella (clinical dx only), Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD ("Secondary Lupus-Like Syndrome"), Osteoporosis, chronic Lymphopenia, etc.; G-Tube; Currently trying to wean off TPN.
Meds: Pulmicort, IV Ceftazidime, Heparin (to flush PICC line), Claritin, Domperidone, Colloidal Silver (used topically), probiotics, Milk Thistle, Ailanthus, homeopathy.