Ugh. I'm on an allergen elimination diet right now because of my 5-month-old's eczema.
The good news is that his eczema goes away when I have eliminated the known allergens. I have also lost a few extra pounds and now weigh less than I did before I was even pregnant.
The bad news is that it is nearly impossible for me to eat out. And I'm spending a fortune at Whole Foods.
I took the plunge and eliminated milk, soy, nuts, wheat, shellfish, and eggs. My son's eczema went away almost completely within two or three days. He also sleeps so much better when he doesn't have eczema problems. I added eggs back in after a week, and he had a horrible eczema flare-up. So eggs are out until I'm done nursing.
I'm also finding that he may have some other allergies that are less common. Right now, my son looks like a burn victim because of something I ate over the weekend -- possibly corn or tomatoes. It is a lot of trial and error, and I want to get these things pinned down before I start him on solids. It's a pain in the butt, but it will pay off when you have a happy baby with clear skin.
By the way, the best thing to do is to completely eliminate the possible allergens and not just cut back. You'll be able to more definitively determine what is bothering him this way. Make sure you keep a log of everything you eat and how his skin is looking.
Good luck to you. I definitely feel your pain.