Yeah ... we were down this road. Eczema, if caused by an allergy can be treated in three ways. 1) A topical cream to moisturize the skin which deals with the symptoms 2) An antihistamine ingested to suppress the allergy 3) Avoiding the allergen completely.
In our case 3) was not an option, as it was dust and everywhere you go there is dust. We went from 100% carpets to tile and wood only. This helped but didn't solve it.
Went to a couple of dermatologists ... who gave the same advice. Waited for 6 months for a recommended Dermatologist and his advice was like Gold ... he had conditions, we were not allowed to see him more than 2 times, and if we still needed to see him, we weren't following his instructions and he didn't want to see us - I like this kind of doctor with confidence in his work.
Used a White Soft Paraffin (not expensive) topically, available from Pharmacy. Washed our son with a Moisturizing bar (not a soap).
Had three Antihistamines, to be given based on skin condition. Zyrtec, if skin was ok. Atterax if skin was worsening, and Vallergan if he had scratched his skin off. We used Vallergan a bit, Atterax a few more times and Zyrtec alot. Now he's 8 and needs the Zyrtec probably once every 2 months. We still use the WSP ... have a life long prescription and that works wonders. It has the consistency of Petroleum Jelly but softer.