I don't know what to do anymore..my 2 year old daughter suffers from hives? Its long, but PLEASE read.?

She has had hives for a little over a couple months nearly everyday. At first, I took her to urgent care because they were huge welts the size of breadsticks and I wasn't used to them so they scared me. Well I've been giving her antihistamine nearly everyday since to relieve her from the hives. We were told we had to wait 6 weeks before getting referred to a pediatric allergist because hives can be from a virus. Well, that is ruled out now, we went to the pediatric allergist on monday (which was an hour away, and the appointment lasted 3 hours...with a 2 year old during naptime-they schedule it for you because hes booked out and the only pediatric allergist within an hour and in our HMO provider list.) They did allergy testing for the top 13 food allergies common at her age and then also dust mites...she was allergic to NOTHING. Which I have a hard time believing, because ice cream and veggie dip makes her break out in hives badly, so does other things, but those are things we have noticed. The allergist told us to give her an antihistamine everyday for two months (we do anyways, and then for one month give as needed (WE DO ANYWAYS.) And then come back to see him in 3 months. Instead, I think I would rather drive as far as I have to and get a second opinion. I am so upset that she has horrible hives and there is no explanation. He also said we might have to get referred to a pediatric rheumatologist I think he called it because she could have an underlying autoimmune disorder, but he also said that should have been diagnosed already if she would have one. Also, her immune system could just be too immature to be picking up an allergy. I am just at a loss as to what to do. Please help in anyway you can. Refer me to any information, any experience. This is exhausting physically and emotionally. There is obviously something wrong.