We are currently in the process of this with my son. His allergist is great. I can send you his info if you want. Anyway, acute hives (1-6 weeks) or chronic hives (6+ weeks) usually starts with a virus, usually an undetectable virus, and is not related to allergies, although tends to be more prevalent in people with hives. The best thing you can do is a high dose of antihistamines (zyrtec, allegra, etc.). We are doing about double the usually dose of Allegra. You can also add zyrtec. Doing the Allegra has fixed it for us. We haven't used Benadryl since starting this almost two weeks ago. Before that we were using Benadryl at least 2-3 times a weeks, and sometimes everyday. Wednesday, I can call, and we'll back down on the Allegra, and keep doing that until we are off and the hives don't come back. The doctor said in kids, usually chronic hives don't last more than 12 weeks max. We're almost at week 8, but haven't used Benadryl in a while. Our allergist said testing in kids doesn't usually show anything, so he prefers not to put the kids through it (saves money, too). If we can't back down on the allergy medicine soon, he'll do tests, but it shouldn't be needed. My son has been happy with what we're doing for now. Anyway, hope this helps. Hang in there. Our doctor was very reassuring that it has nothing to do with what we were doing, or changes in our house. GL!