Middle finger..rt hand sudden excruciating pain at proximal joint..worsened if any movement...grip progressively weaker(no trauma prior to pain)..?

Trigger: This is either a trigger finger or a sprain. Given your age this is most likely a trigger. Most resolve with injections of cortisone.

Specialist consult: You need to go see a hand specialist, likely and orthopedic surgeon (they do more than surgery) to determine if there is any damage in the hand causing this pain. Could be a number of causes but only imaging and a consult with a specialist will tell you what you need to know to initiate treatment.