It is hard to say what has caused the decline of your cherry tree.  It could be a freeze. It could be a pest or disease.  You said you planted it last Spring.  It takes a while for trees to get established. One very important thing with new trees is winter watering especially in our Colorado climate.  Lack of water over the winter could be the direct culprit or led to a weakened state that made it susceptible to other things.  Attached is a CSU fact sheet on winter watering.  https://extension.colostate.edu/topic-areas/yard-garden/fall-and-winter-watering-7-211/