I was reading this article
this morning and thought that it might be contributing to your problem.
When a tree
is transplanted it does not necessarily have the capacity to carry all of it's foliage. When this occurs, the tree
will sacrifice it's upper branches and keep the lower portion alive. It sounds like what your tree
is doing. This does seem to be a rather severe case so I assumed salt, coastal CT.
I hate to give advice without standing next to the tree
but I would cut the tree
back some. The roots will then have less tree
to try to keep alive. I think your heavy watering was/is a good thing and I would suggest doing it during any dry spell, the tree
needs the water and it flushes out the salt.
How you cut it back matters. You want to cut off the top, as much as practical and with a single cut. Something between 25% and 33% of the tree
should do the trick.