Oh, I'm so sorry-- chronic hives are miserable.
I really hope that you CAN find the cause. The bad news is that it's possible that they are stress-related (first occurred during a move, right?) and that is why they aren't responding to antihistamines at all. Of course, the hives themselves are also stressful.... well, you can see where that is going right?
Have you had a history of eating nuts regularly without ill effect? If so, it might be a good idea to consider a food challenge with your allergist-- while adults can and do develop treenut allergies out of nowhere, it doesn't really sound like this is necessarily FOOD related specifically. Unless it's something that you're eating a lot of without knowing. The vast majority of adult-onset food allergies are to nuts, seeds, and shellfish, if that helps you.
I have to wonder about possible insect bites (bedbugs? fleas?) or maybe insecticides in your new home. Other common triggers for hives include soaps, perfumes, detergents, etc.
Again, I really, really, really hope that you can figure out a trigger that you can eliminate.