Hello doctor I feel lack of stamina all the time. There is a feeling of tiredness, lack of energy and frequent headache. Though I dont do much physical activity, I get tired soon. I have been taking Cobadex _Z for last 10 days but there seems no improvement. My diet is OK with all green vegies. However, B12 test showed lower level of B12, less than minimum. It was 212.Is it the result of this or something else Pl. suggest.