Has anyone had 'stains' , round or ring-like dark marks on their skin because of mercury?

I have these in my scalp. The edges are dark-red, almost black. Before I noticed them, I had this intense burning sensation first on my neck and then on my scalp. This lasted many days, even weeks. The marks do not itch or anything.

What is it in my scalp?

Fungal infection? If so I have found collodial silver or apple cider vinegar applied directly onto area helpful.