Hives are an immune response. You've got something that has either built up in your system over time or else something that was added to your system whenever the hives first began. If you've tested negative for allergies (I assume it was something your docs did) I've got to wonder about either a reaction to a perfume, soap, lotion, laundry soap, fabric softener or even shampoo or maybe a reaction to a food/consumed item that you don't maybe usually think of as an allergen.
Since hives are classified as an auto-immune response, my first question was how much nutrasweet do you drink? If you are drinking a lot of diet drinks you may have come to a point where dropping the sweetener habit will allow your system to clear and it might be that the hives are a response to long term exposure to the chemical bath that Nutrasweet gives us. If you google urticaria + nutrasweet you'll find some reading on the subject. You might find it helpful (or you might think I am nuts!)
Good luck! I'm sorry you feel frustrated!
Laura
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