Often cherries will have something called girdling roots. That means that, instead of spreading out from the trunk like your fingers from your wrist, the tree's roots get crossed one over another. Then as the tree grows, the root on top slooowwwly strangles the one beneath as it grows.
The remedy is to take a saw or an ax and cut the top root, releasing the bottom-strangled root. Problem... this works for roots on the surface. If you see girdling roots on the top of the ground, you can double-dog bet that there are 3X as many girdling roots underground. Where you can't get at them without killing the tree anyway.
I'd just recommend applying deep-root fertilizer. That'll keep the parts of the tree that are still vibrant, alive longer. Job's spikes are okay, be sure to push them down deep. Or get a tree company to do it commercially.
Hope this helps,
Dot
