My younger son is 14 months old. From the time he was about 2 1/2 months old, he had really bad eczema. I exclusively breastfed him. I cut dairy, eggs, soy, and nuts out of my diet for one month. His eczema improved dramatically, but he still had flare-ups every once in a while.
When he was six months old, I took him to a pediatric allergist, who told me that all allergy tests (skin patch or blood) are quite inaccurate. They can be a helpful tool, but they cannot guarantee a definitive allergy diagnosis. I didn't bother testing my son for allergies, since I had a fairly good idea of what he was allergic to. Plus, infants and toddlers' allergies are changing all the time, so I didn't want to constantly subject him to all of that testing.
Anyway, now that I am no longer breastfeeding my son, I have pinpointed his dietary allergies (milk, eggs, soy, nuts, legumes). Right now, he, my daughter, and I are going absolutely crazy because of the tree pollen outside. We have hives, sneezing, and wheezing going on here. I wonder if that is what is bothering your daughter as well.
Are you sure your daughter isn't allergic to milk? My daughter, who is now six, had no reaction to milk the first two or three times I exposed her to it, but then one day when she was 10 months old, she dipped her hand into the whipped cream on my Starbucks drink. She had full blown anaphylaxis without even ingesting it, and by the time I got her to the ER, the triage nurse thought she was a burn victim because her face was so blotchy and swollen.
My son is coping right now by me giving him 1/4 teaspoon doses of Benadryl about every 6 hours. It keeps the eczema at bay and he isn't sneezing or wheezing too bad. Good luck to you. I'll bet your daughter is so uncomfortable that she isn't sleeping well. Not fun.