Hives and itching after gallbladder surgery

I'm a 51 year old female who had her gallbladder out ten days ago. A couple of days after surgery I developed hives on my abdomen from under my breast, on my sides down to my groin area. Benadryl isn't working, and I don't seem to be affected by food, or the material in my clothes. I've lost a lot of sleep and am looking for some relief. I've never experienced anything like this. Has anyone else had issues with severe hives after gallbladder surgery?