As someone who has gone surgery on both hands for Carpal Tunnel Syndrome, I can only echo what others have said. Get it checked out. If you don't you could be putting your ability to play at risk to say nothing of all the other functions we rely on our hands for.
I also suffer from arthritis in wrists and back but with a little help from the medical people am able to keep playing although I have had to alter my banjo style to using thumb & index finger.
Look after your hands and keep on picking