I don't know what the weather's like there currently - in the UK, we've been having much colder weather than usual at this time of year, and many plants are suffering a bit from it, especially Acers.
I'm not sure what the black spots on the tree are - if they're on the trunk and branches, the woody parts, it might be scale insect, but usually you'd see white fluffy stuff around the black spots.
A photograph of the tree would be helpful - one close up showing the black spots, and one from further away, showing the tree branches.