Young fruit on my cherry tree turns black and falls off. Help! [View all]

This is the third year now that most of the tiny cherries turned black and fell off of my mature cherry tree. There are only a few full-sized fruit here and there. Four years ago the tree was covered with tons of beautiful, tasty cherries. What could the problem be? I live in an area that's famous for growing cherries and we didn't have a late frost. I know they're getting enough water. They've been given compost for fertilizer. I don't know what type of cherry it is so I don't know if it's self-pollinating. It could be a Bing, it looks and tastes like it. Do they need a pollinator? My neighbor cut down a couple small cherry trees in his year a few years back.....maybe that was my tree's source for pollination? How far away do the pollinators need to be? I know this community is full of cherries but maybe none are quite close enough.