Hi.. Thanks for the query.. Hives on different parts of body seems to be most probably due to allergic reaction and in case if you are no more in contact with your nickel buckle of belt then can be probably due to other reasons.. It can be due to an allergic reaction which occurs when skin comes in contact with certain agents that your body is allergic to like skin cosmetics, detergents, soaps, fragrances,leather, latex, poison ivy etc.. -Another cause can be food allergy or side effect of medicines.. I would suggest you to consult an Emergency room and get evaluated and a thorough clinical evaluation and investigations like allergic tests like Patch test, RAST test, food challenge test etc can help in diagnosis and treatment can be done accordingly.. You can be advised to take oral anti allergics as well as injectable steroids for relief.. As of now you can take anti-allergics like Levocetrizine, Allegra to control the itching and swelling.. Do cool compresses.. Application of calamine lotion can help in soothing the skin.. You can also be instilled an Immunotherapy that will help in reducing the severity and frequency of allergic attack.. Hope this helps.. Regards..