I had trigger thumb for almost a year. I could not bend my thumb joint on its own and when it did get bent it was excruciating. I did not want to see a doctor because I knew from other people I knew who had experienced trigger finger/thumb that all the doctor would do is give an injection of cortisone, which I did not want!
My sister-in-law suggested that I try drinking distilled water, because she had been using this method for 2 years to relieve the pain and immobility that she used to have in her hands; prior to this she could not make a fist. Every time she would stop drinking the water her pain would return. So with an open mind, I tried it and after 3 or 4 days I was able to bend my thumb on its own!! It was still a little stiff and very slight pain.
I used distilled water in coffee, tea and cooking if it was to be consumed, i.e. soup , etc. It is absolutely amazing and really works. It has been a month now and I have full mobility again and no pain!
As a bonus all of my joints feel better. So try it before anything else.