Ged
Is this something related to requiring anti vibration gloves, an existing problem or the way that you are holding the trigger, possibly for extended periods.
Is it worth looking at a Suttner? trigger - much easier on the grip & whole hand generally.
I don't think that antivibration gloves will help. I would look at the easier trigger and a glove with a different padding set up to take some strain from the thumb.
Good luck
Rob