I had my tendon sheaths rebuilt on my right fingers using a "spare" tendon in the wrist. I've also had carpal tunnel taken care of.
My fingers were like yours, I couldn't open them. Then they actually started creaking when straightening them. The tendon sheaths were failing, swelling and not allowing my fingers to open. Hurt like hell. With you, might just be some swelling of some kind, but if you can, see a hand specialist if its effecting your life. My condition would have worsened to the point of having joint damage if I didn't get it fixed.
Dont suffer too long before getting checked out, just dont rely on a regular doctor. They dont know, see a hand specialist.