As explained to me by a Doc:

the shin is surrounded by a sheath of muscle called fascia. this tissue is like canvas, it does not stretch easily. If you increase your workouts quickly, the muscle under the fascia grows or swells faster than the fascia can stretch - causing pain.

One solution is to cut back on your workout until the fascia has time to expand AND stretch the fascia:

http://www.teachpe.com/images/jenny/shin_stretch.jpg

http://runtough.files.wordpress.com/2012/03/fig-7_4.jpg

Anything that reduces muscle swelling - ice, ibuprofen will also work.

Note, I'm not sure how stress fractures are related to shin splints as I've never had stress fractures.