Searching for a time travel novel I read when I was a teenager in middle school, circa 1995, about a kid or young man who finds some kind of a marble or pebble or pearl or something that gives him the ability to travel through time.
My recollection of the whole thing is very vague. If I remember correctly, he uses the object more and more excessively throughout the novel and sort of like what happens in that movie "The Butterfly Effect" with Ashton Kutcher, he gradually realizes that each time he travels back in time and changes something he ends up just screwing things up more and more until his life just about completely falls apart.