I got this info from a Chicago alternative M.D. who has treated thousands of eczema patients -- the vast majority successfully -- by identifying and eliminating the foods they are allergic to. My wife was one of them. She was going out of her mind with eczema. When she eliminated dairy, wheat and eggs, her itching stopped within a few days, and within a few weeks the rash disappeared.
Another clue to identifying your food allergies is that people tend to crave the foods they are allergic to. Take a look at the foods you eat regularly, and ask yourself how you would feel about never eating that food again. If you're indifferent, that food is probably okay. If the thought of eliminating it forever is painful, that could indicate a problem.
In my daughter's case, we got rid of her eczema with Bio K+, a very powerful probiotic.