What causes a finger or two to twish ot shake without you doing it yourself.?

Depends: There are several possibilities ...Most likely is stress and increased caffeine intake, along with not enough sleep or nerve injury if hand forearm recently traumatized but also carpal tunnel issues as well to name a few.

Many things: Finger twitching can be due to many conditions, most of which are neurologic (nervous system). If your symptoms are significant or concern you, you should see your primary care physician or neurologist for an evaluation.