Hi, welcome to the forum, your symptoms are suggestive of urticaria, secondary to exposure to allergen and mediated by IgE antibodies. Your body is known to hypersensitive to certain things.
Stinging insects, aeroallergens (uncommon), Foods and additives like Milk, egg, peanuts, nuts, soy, and wheat are the most common agents to cause generalized urticaria in adults.
This triggering factor should be identified and should be avoided. A skin allergy test can be useful.
Treatment includes anti histaminic and glucocorticoids against prescription. I suggest you to consult a skin/allergy specialist. Take care and regards.
Hives are generally caused by an allergy, although there can be other irritant causes as well. I know several people who are sucessful at controlling their hives with Allegra (generic works just as well) or some Zyrtec.
If you really want to know exactly what you are allergic and what is triggering your hives you should see and allergist and have testing done.
Feel better.