Suffer from metal allergy? Poor husband..

My husband put on his best suit for a wedding and after he got home I saw a bloodstained shirt in the laundry basket. Actually the condition of his skin – around abdomen- has been becoming dry and rough since last month. Although he has had some mild itching, it does not keep him awake at night. But the rash is continuing to grow, with no sign of improvement.

My husband was examined by a physician (dermatologist) and was told that he has a belt buckle allergy. He is otherwise in good health and has no history of skin diseases.
Could this be a belt buckle allergy? What else might cause a rash with this appearance?

I’ve read some of the news about metal allergy and they said that that happens suddenly or by chance without an apparent cause.
I would hate for that to cause me some troubles ’cause I wear my piercing on my days off.