Any Suggestion For Suffering From Chronic Urticarial?

Hwllo Dr. Pathak, I have chronic urticaria for about 3 years now. I could not find any pattern or any food that makes my condition worst. I do feel that it is related to heat, so for example, if I am sleeping and feel itching in a particular body part, its related to heat somehow. Anyways, have tried cetrizine, levocetrixine, laratidine etc and now on 50 mg Doxepin at bed time with 10mg cetrizine. Doxepin seem to be helping when I was on 25 mg nightly dose but after 2-3 weeks I wasn t sure if it was helping, so doubled the dose to 50mg. It s been 2 weeks on 50mg dose but still not feeling any better. Thinking of going back to levocetrizine (2 tablets of 5 mg each) along with 50 mg Doxepin - all together at bed time. Will this worth a try? I won t die on over dose :) I am hoping.