For the folks who can't afford expensive patch testing, the alternative is an Elimination Diet and stopping using all detergents and soaps. A three day fast is not sufficient for this, as allergens can manifest a reaction for a while after exposure.
Introduce things one by one to see what causes a reaction. It might be a lot of different things too. Also, an Ohio Uni study found stress and anxiety increased the severity of allergic reactions, so trying to eliminate them might be a good strategy as well: