I don't have what I consider hives but I do have swelling in odd area for no reason. It has been in my feet, my hands, my face and my throat. After seeing my allergist several times and having several allergy tests done I was diagnosed with Chronic Idopathic Angioedema. I wasn't able to learn tons about it so far, there seems to be limited information online. My throat has swelled up 3x now and I carry an epipen, I would assume you should as well. I can tell you to find out if you have CIA it is a series of bloodwork, there is even a chance people inherited it. I was put on Zyrtec as well and I add Zantac into my day as needed. I haven't had alot of success so far but we are still working at it. Might be work looking it up and mentioning it to your doctor. I wish you luck!!!!