You sound a lot like me, I started taking lanoxin for an afib episode and that medication gives me so many arrythmias that I could not handle them. I hear and see that many doctors use lanoxin for afib and I also see from reading that many say this is not the choice for afib unless you are in constant afib. I look at the news groups as well and there are many helpfull tips there as well. I don't remember your specifics since you did not state your age, how long you have had this, what treatments or testing has been done or other facts but I wish you luck with this as well. Ice water,,,,, sounds like you are responding to a vagal stimulation, which I find I can control my arrythmias with as well.
Yes, all medications for afib can have potential side effects such as you describe. I do not think changing brands will help much, but changing to a different medication may be very helpful. Check with your doctor about stopping the medicines you are on now and starting a new medicine.