Actually you may be right about baking soda. Too much baking soda will deplete potassium from your body and low potassium levels will cause heart palpitation. However do not take potassium on your own without consulting your doctor, taking too much potassium may be dangerous, specially if your kidneys are lagging. Low Iodine levels may also cause irregular heartbeat.
Adrenal fatigue or imbalanced cortisol (too high or too low) levels may cause heart palpitation.