If there's some nerve entrapment taking place,as you attempt to bend your index finger
, this would explain the excessive pain
If this is very important to you, take your time and save the 5K and get it done properly.
I had a couple injuries, one while skiing-broke my pinky- and another one
while sparring and hurt my back badly, so I had to quit martial arts.
I'm OK now, but I have to be careful HOW I do certain things, so extreme sports are definitely out,lol!