A rash due to a metal necklace?

I wore a ball chain necklace the other day and i suspect i may have been slightly allergic to one of the metals in the alloy (probably zinc as i have issues with copper as well). It left an itchy bumpy and slightly stingy rash on the back of my neck, but isn't red or en-flamed looking. Its been irritating me for a couple of days and i want ot get rid of it before i leave scratch marks on the back of my neck. Any ideas as to how i can heal it?