I had the same "problem" a year ago before I even knew about AF.
Later I found out that I'm extremely hypoglycemic and I think that's what was causing it.
I don't know much about NB and heavy metals connection but if I were you I would look closely at your blood Sugar levels and how it reacts to alcohol being present in your system.
Try to maybe eat very low glycemic foods or avoid drinking on empty stomach.
Other high protein and high fat foods are very helpful before you drink( I'm russian, trust me:)))
As for me I had to quit drinking for good eventually.
Hope it would help
Good luck!
P.S: Few handfuls of almonds throughout the day do great for me to keep the BS levels at least above 80.