Cherry Tree problem

Ok, I don't have a picture right now, but for the past two summers the cherry tree in the front of our house has been giving us headaches and it's already starting again.
It usually starts off nicely, lots of flowers, lots of leaves, beautiful. But then the flowers die way too fast, and some of the leaves start getting holes in them (that's the stage we are at now). As the season progresses, we will end up with a total of 4 or 5 underdeveloped and blackened baby-cherries, increasing amounts of holes and blackened, crumpled-up leaves (that's when it will be worth actually taking pictures of the problem).
I have noticed another cherry tree in an adjacent street with exactly the same problem, but that is a much younger tree. I did believe that our tree might be just past its time, having heard that cherry trees do not get much older than 25 before generally putting on diseases and having to be felled. But if even a much younger tree is afflicted this can't be the case with our tree can it?
It's a bit of a shame as the tree is really lovely otherwise, nicely grown, 2 storeys high (which, however, would also make spraying it with any sort of chemicals a bit tricky...)

 

Curled up leaves make me think black fly.
We get them on our 10 year old fan trained cherry.
If you can get a good look inside one of the leaves you might get a clue. But if the tree is a monster spraying it could be rather a problem.