Young fruit on my cherry tree turns black and falls off. Help!

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.