How much sugar did you eat that day? Chocolate should never be eaten on its own, just like eggs (due to leucine content). Liver itself is pretty high in protein too, promoting hypoglycemia if you don't eat it with sweet stuff.
Just sounds like hypoglycemia with high adrenaline. I doubt it's the copper, especially since you got it from food.
EDIT : At the time, I was taking vitamin A. Later on, I found out that stopping it significantly improved my thyroid function (making it quite easy to reach optimal temperature).
At first I thought that the supplement was an allergen, as Peat had told me months before that pregnenolone and vitamin A supplements often introduce impurities because of new techniques.
But, when trying small amounts of calf liver (with coffee) I was puffy again, and felt tired.