Do you stick your left hand into dish suds doing the dishes etc?
Do you wear gloves when cleaning etc?

I ask because I am allergic to something in the water on vacation, and my left hand and forearm get the rash worse and faster than any other body part! (I would be pumping the pump with my right.). It took me a while to figure out this rash, and we zeroed in on the algae bloom there, since it only comes during a certain time of year.