Nickel allergy is extremely common. I've got it. It always worsens with time and exposure. Untreatable except by avoiding contact.

I'm okay with the keys on my tarogato, clarinets and flutes, but the house keys in my pocket produce a raw bleeding patch on my thigh unless I keep them in a leather pouch. My brother has it much worse than me - his whole face swells up from contact with dental instruments.