What's the best way to reduce odor in my well water?
You said the water smells bad unless run for 10 minutes this points to air in your pressure tank. With a failed bladder in an old tank air contacts the water in the tank and it develops a bad taste/smell. If I wanted to sanitize a well that deep I would pour several gallons of bleach into the well and let it sit for at least several hours then pump the well until the bleach smell is gone. As far as the stone shower I would not be concerned as much, if you want to sanitize that I would use a 3% hydrogen peroxide and water, spray the stone work then rince. Since your smell disipears after several minutes check your pressure tank as it may be the source of the bad smell.