After golfing last week my indexfinger and thumb are very stiff and hurt a lot to bend. how do i treat this?

Stop gulfing for now: You overdid it. Time to rest. Take an ant inflammatory such as motrin. After a few days to a week, get back into it gradually. Still having pain, take mor time off. You may also need lighter clubs.

Questions for you: Do you mean your right hand? Are you right handed? Do these fingers hurt when you bend them? There may be a bit of inflammation in the tendons which flex the fingers. If you are a new golfer, this may improve with rest and maybe a change in your grip later. If you are a frequent golfer, you may also look at your grips, ball compression, or what you were hitting to see what caused this.