Love having a doctor on the team! :) So grateful for you!

Yes, the locking up of the fingers is called trigger finger and is caused by tenosynovitis, or inflammation in the tendon and soft tissues. I have gotten this, too, and immersing in cold water helps, although warm/hot water may feel more soothing for some.

Yes, I have to take medication Potassium Chloride for Oral Solution USP 20 m Eq

Yes, I frequently massage my fingers and hands to keep my blood flowing.

Yes....I have this every morning when I wake up. It is very painful 😒