Hand Tremor

[Twinsplusone40]

I am a 55 year old female.  I play competitive tennis.  Recently the base of my thumb started hurting in the joint accompanied with some index and middle finger tremor/twitching.  Finally it became annoying enough I went to my orthopedic surgeon.  The thumb base was very sore.   He said I had arthritis in the joint but wasn't sure what was causing the tremor.  I have to preface  this; a few months prior to this I would wake up and that hand would be completely numb.  However, it is not doing this currently.  He did give me a cortisone shot in the joint and we are waiting to see if this helps.  Is this nerve inflammation or the begins of Essential Tremor.  Certainly angles it does not twitch.  It does not twitch at rest.  Thank you!