Could Chronic Hives Be Due To Thyroid And Hashimoto's Disease?

I have had chronic hives for 2 years now and am taking doxepin, hydroxyz hcl and cyproheptadine, all oral and sometimes I take Benadryl from a dermatologist MD. I'm told that it is caused from my thyroid and hashimoto's disease. Is this what I'm having to deal with or is their something else causing it. Oh and I have been tested for all allergies. I also see a phyciatrist. Pardon I spelling.