What Can Cause Stabbing Pain In Wrist?

Good morning. I ( on occasions) have a stabbing pain In my left wrist, to the right of the centre. It comes and goes with 'no reason. It stabs for a few seconds (horrible) then goes for a minute or two then returns. It keeps me awake and I need to take strong pain killers. It is centralised it that area with no pain in wrist, fingers or arm. A specialist told me it was Ulna!! But I have read about this and the symptoms are all wrong. Please try and help. Regards Deana