Wool is an instigator of eczema breakout; so it looks like you may have found the allergen. The wool is considered a harsh fiber and it also absorbs the moisture from the skin. The skin's moisture barrier serves as a protective layer against harmful irritants; consequently your son's layer of protection is being compromised by the wool fabric. 100% cotton fabrics are suggested as the best type of wearable fabrics for eczema sufferers. Allergens enter the body through these five areas: skin, nose, mouth, eyes, and ears. In each point of entrance, the body has its own defensive protection. For the skin, it's the moisture barrier. I think you may have indeed found the culprit of your son's breakout.