I have an anecdote about zinc. I have 50 mg tablets and started taking 1/4 tablet every day in May. I already eat a lot of meat, chicken and fish (apologies for grossing out all the vegetarians here). After about two weeks of the supplements, I developed an itch on my chin that was impossible not to scratch. I tried calamine lotion, various ointments and cortisone cream but nothing would stop the itch. I rubbed or scratched so much that my chin became raw, and after a couple of days, crusty, then flaky ... none of them an attractive look on me.
I stopped taking the zinc and was fine until mid-July when I started the daily zinc again and got the extraordinarily itchy chin again. I can’t prove it was the zinc but it hasn’t recurred since I stopped taking it daily. I now take 1/2 tablet (25 mg) once a week. Maybe one of the supplement experts here has heard about this?
I’m going to take a guess at this. you’re body is likely not absorbing metals very well. Sulfur and methionine digests metal. Garlic is the best source for sulfur. Brazilian nuts for methionine.