Hello and thank you for using HCM. I carefully read your question and I totally understand your concern. Heart palpitations has to do with electrical issues in the heart. There are some electrical impulses that generate in a part of the heart different from normal sinus rhythm that cause a premature heart contraction. During this, you might experience a palpitation, e skipped beat, an anxiety sensation. This electrical issues might happen because of different reasons like stress,coffee or alcohol consummation or pathology s like anemia, hyperthyroidism, active infections or congenital heart diseases. As you explain, you once had anemia, and we don t know if you still have, You have a swollen gum, this meas an infection of your gin give, an active infection. These are some factors that might cause heart palpitations. So, the first thing is to menage your tooth infection, your anemia if it is any. I will also recommend a cardiac echo and a blood analyze. There are not specific foods to calm heart palpitations. There are some thinks that you should avoid like caffeine products, energy drinks because they rise heart frequency. Sometimes regular physical activity improves heart frequencies and this palpitations. So, I will recommend you to resolve your tooth infection, follow this instructions and thinks might improve. Hope I was helpful. Best regards.