I have a gorgeous tree against my house that is our favorite. It looks like its experiencing some disease.
If the pink flowers hang in clusters and the trunk has horizontal lenticels (lines) it is probably a Kwansan cherry. If the tree is fairly small in stature and has very small flowers it could be a plum. The best way to tell is to take photos to identify, look at tree books and or other photos to compare the leaf and flower structures.