The reason I asked if you have pets is that they can get oils (like the urishiol from poison ivy) on their fur and it can transfer to humans that way.
Trying to research a mystery rash is very difficult and frustrating. Don't automatically dismiss plants that one might have touched in the past without adverse consequences. Wish I knew more about what would be around in ID recently to give someone a rash.
Clearing out brush may be it though, it's possible to get a rash from dormant but very much alive PI (or poison oak if you have that there) vines, live roots. Even freshly 'dead' leaves can still have urishiol on them. As an oil, it takes an unknown quantity of time (depending on weather conditions,) to degrade. Urishiol can also get on tools and clothing, and pass to skin from there.
