It was probably just eczema, not psoriasis. Eczema is partially an allergic reaction and partially liver toxicity. Psoriasis is a chemical imbalance between cAMP and cGMP. I think I already posted my write up on psoriasis. If not I will try to find and post it.
Silica can help with eczema by increasing collagen in the skin. This gives it more strength, which decreases the risk of skin damage that can contribute to eczema.