I think it may be too late for Niacin, like Silver when it plates out in the skin at the wrong charge, the particle size gets too big..
That said, ALA takes out Silver plates like that and certainly when my skin used to go nuts, during my first attempts at +50mg Of Lugol's, first larger doses of Se then ALA worked for me.
Somewhere is the post on ionizing Saunas and why they may work so well on these skin issues becomes apparent when you take this kind of plating into account.
..hmm, HC used to tell people to O3 - Ozone bag. Either in special O3 - Ozone sauna tents or suits..
Mike may wanna invite you to his place and crank up the juice in his trailer :)