Check out some of my stories. Virtually all of them feature detailed changes that range from "unpleasant to really unpleasant" though I wouldn't say any cross the line into outright "painful." Also a lot of the trial that I put my characters through tends to be psychological rather than physical.
http://www.fictionmania.tv/searchdis...html?word=4236
Look up some of my old post threads here on this forum if you're concerned about self plugging. Most people have really enjoyed my work.