I was b12 defiecient and anemic and put on iron and weekly shots for b12 for a month then dropped to once a month! Been experecing low heart rate at doctors office 40 s did Ekg came back fine but low heart rate! Put me on heart monitor for two weeks now. Experencing shortness of breath, fatigue, etc! I only take vitamins, calcium, multi vit, iron x2, and the now monthly shot of b12. any suggestions? Is anything I m taking doing this?