I've been on flecainide 100mg twice a day for the past 5 months. stopped it four days ago and my hr is still really low. is this withdrawal or has my arrhythmia gone away? how long until heart goes back to normal?

The half life of: Flecainide is 18 hours so it will take two to three days for the drug to be out of your system. Your HR will recover but your arrhythmia will most likely return too. Discuss this with your health care provider and ask for a referral to an electrophysiologist who can map and ablate your arrhythmia. This will be a cure so you won't need medications anymore.