What Causes Swollen And Painful Palm?

Hello, I am a 67 years old female. I am also on Blood pressure medications. I woke up this morning with my Right wrist and palm swollen and painfull. I ahve difficulty openning my 3,4 and 5th. fingers. I tried swimming, too painful to use my hand. What could be the reason, no previous injury to my hand or wrist. Thank you. Margaret