How bad is the pain? Right now I would suggest rest and ice (frozen peas) until you seek proper advice from a physiotherapist or doctor. Voltaren might help reduce the pain and you could immobilise the thumb with a loose bandage around the whole hand so that you are not tempted to use it. There are physios who specialise in hands, wrists, arms and shoulders. I would not try to keep using it in pain lest you make any damage worse and slow your recovery. Perhaps you have irritated the ligament by overuse and not torn it. It would also be a good idea to revue your technique in case your thumb is being misused. How do you think this came about?