I Have Been Retaining Water In My Fingers Both Hands,

I have been retaining water in my fingers both hands, but more so in my left hand. I notice it while I sleeping, I wake up with swollen knuckels; after I move around then go back to normal. Then again re-swell when I walk/run on the treadmill, they quickly go back down, when I am done. I am a 55 year old woman.
In good health; with controlled blood pressure (was on medicine for it, but am now off)