Female Age 27, 5'2, 155ibs. Hello, not very often (maybe once or twice a month over the last 6 months or so) I notice my heart fluttering very quickly, it feels quite strange, like it is rapped in a knot or something- but does not hurt. Should I be concerned? (also recently had an influx of weight gain and found out I was low in b12...around the same time this started)