Arnica vs. Rhus Tox — How Do You Decide?

This question came up three times last week in different threads, so it deserves its own home: when you've got a musculoskeletal issue — say, a sore back after moving furniture, a tweaked knee, or general "I overdid it" soreness — how do you decide between Arnica montana and Rhus toxicodendron?

The classical distinctions most of us were taught:

— Arnica: Trauma, bruising, "sore as if beaten," the bed feels too hard, wants to be left alone, often used prophylactically before/after dental work or strenuous exertion.

— Rhus tox: Stiffness that's worse on first motion and better with continued movement, worse from cold and damp, the classic "rusty gate" picture, restless, has to keep changing position in bed.

In practice they get used together, sequenced, or confused. I'd love to hear:

1. What's your go-to mental shortcut for differentiating them? 2. Have you had a case where you thought it was one and switching to the other changed everything? 3. Do you use Arnica topically, internally, or both — and at what potency?

I'll note up top: nothing here is prescriptive. We're comparing notes, not treating anyone.