I had the exact same problem whrn my now 4 years old was two:
There are many things to try, and I am sure you tried almost everything! Have you switch your laundry detergent as well as the soap and shampoo to all natural without harsh chemicals? I am not trying to promote a brand here but trying to help, there are several choices and different brands today.
When my daughter was 2 years old, she had eczema on her feet, it was really bad, at the point that she couldn't stay standing because it hurted and she used to scratched against the floor, at that time I was starting to be concious about the checmicals and I was replacing some products to non chemical ones. I tried diferent creams for fungus that didn't work and the doctor prescribed corticoides and a moisturizer.... I was very concerned with the coritcoids so I remembered that I had a trial size tub of Renew lotion in my purse and showed him the lotion and told him that according to the manufacturers, there is no better lotion than that to help with eczema or dry skin....I was pretty new with that brand back then so I wanted to be sure about it rather than experimenting with my already suffering child. He told me to try it because the ingredients where so good! I started using it twice daily (morning and night) the eczema was gone faster than I would ever imagine, never came back but as soon as I realize her skin is a little dry I apply Renew. Knowing that it is naturally based without any harsh chemical or corticoids is a relief. I never had to purchase the prescriptions. I am also using everything from the same company now, but I am not doing the business side, I can still enroll people in the company if they want to purchase there but don't want to work the business because I do jewelry and I am doing that full time now.
If you would like to give them a try I can help you with that without the sale speech (check http://melaleuca.com/ and follow the tour to know more about them).
This products are the best quality you can find at a great price, they are not more expensive like anybody can think. I have been a customer for over 3 years now!Let me know if I can help.
I really hope you get relief soon, I've been there:)