Three Of My Fingers Went Painfully Down And Won't Go

Three of my fingers went painfully down and won't go all the way up. Happened 5 months after I had open heart surgery to replace a valve. Rop of hand has a big swollen lump, painful wrist. The doctor and techniciens I saw told me they never saw that before. MRI showed nothing wrong with my hand. I have regular arthriris but no deformed fingers.