I'd imagine it's calcium build up (yeah, arthritis) that's impenging a nerve. Our youth does catch up to us eventually. I used to ride dirt bikes, dune buggies, bicycles, street bikes, hot rods, worked construction, and now I'm worn out! Three back surgeries, shoulders messed up, wrists, neck, knees, etc, and I'm almost 47 and on disability!

Take care of yourselves while you are young and you'll live a more fruitful life without pain later on.