I don't know about the rash problem, but it may come from fillers used to make the pills.
What I know about generic thyroid
meds is this;
Synthroid, Levoththroid, Levoxyl
, and all name brand forms of Levothyroxine are held to stricter manufacturing guidelines. If the label says 100mcg, the allowance of error is ten percent plus or minus, including the strength at the expiration date.
With generics, the allowance for error is plus or minus 25%.