If you use liquid soap, it's wise to check the ingredients
According to this information reproduced from an article in The Daily Mail from Dr Martin Scurr's "Good Health" page, the EU now permit stronger concentrations of a preservative called methylisothiazolone. This is found in liquid soaps, cosmetics, shampoos, baby wipes and bubble baths. It is also found in household products such as paints, adhesives, printing inks, polishes, detergents and fabric softeners.
If you have been unable to find the trigger for your eczema, it would be well worth checking the ingredients of the products you use regularly. Whenever possible use organic or natural products and be aware of the ingredients of household goods as well.