Yes, it is very possible to be allergic to metals. This kind of topical allergy is called allergic contact dermatitis and the most common allergen is nickel (which is commonly found in belts). You should follow up with your primary care physician
regarding your symptoms and history to determine if further testing or treatment is required.
Allergic contact dermatitis is a type of delayed sensitivity to a skin contact with specific allergens, like metals or dyes. Usually this results in the development of skin redness with some swelling and possible vesicle or hive formation.
When discussing your symptoms with your physician, you should pay close attention to the pattern of when your symptoms develop. Do they develop with a certain belt or pair of pants? Or when you use rubber gloves or hair dyes? Or when you go camping and touch new plants? All of these questions and the pattern that you find can help your physician determine what compound may be causing your allergy. If deemed necessary, skin patch testing can be done to determine possible allergic triggers. The main treatments for allergic contact dermatitis are avoidance of the allergen and topical corticosteroids.
You should follow up with your primary care physician to discuss your symptoms, need for further testing or Allergist consultation, and to determine best management in your case.