Recently, I have arthritis in my left thumb. I don't feel any pain and the thum is still very flexible (I can bend to form an angle close to 90 degrees). Byt a few times in the day, I would feel something grinding or very rough inside. Then I have to hodl the finger and help it to move a few times until I hear a little 'click' sound, and i would feel fine until it happens again. Please advise. Thank you.