Why would a cross hurt?

When I was little I was raised to be Christian, but I have sense then strayed from that path an a few years ago I was playing with a metal cross and laid it on my bare chest and at first I though oh it's just cold nothing to worry about, so I laid my hand on it to warm it up an this burning sensation intensified, sense then any time a metal cross is on my skin it burns and leaves a red impression even when no pressure is applied. Can any one give me an explanation to this?

You have been watching too many Vampire movies.A cross cannot harm you,except in your imagination.

I knew someone a few years ago who was given a gold cross on a necklace, and it left what looked like burn marks on her skin whenever she wore it. Turns out she's allergic to gold.

If the cross is hurting you, you may be having a reaction to the metal, but not to the symbol itself. It's just two pieces of metal overlapping one another; it's only "power" is in the belief one might have in it.