who only by moving can balance

For the past week or so, the base joint of my right-hand little finger has been very sore, particularly on the palm. Range of motion is generally normal, except immediately after waking; at that point, the finger is "jumping" between different positions along its length (bent/partially extended) as I flex it, accompanied by a general feeling of thunk. This gradually wears off over the course of half an hour or so. Sensation is mostly normal (if slightly tender).

Potentially relevant things to consider: hypermobility-type EDS; RSI.

Suggestions/input/advice welcome; I have not yet tried sleeping in wrist splints but suspect that's my next step.