About a week ago, there was a discussion regarding Pine trees turning brown and dying. I was not the original OP, however was having the same problem with a 30/40 foot pine. OP was in Baltimore and I live in Texas, so water and/or climate didn't seem to have any commonality.
Today (09/23), I had a tree removal service out to cut down my tree. While it was on the ground, about 20 feet up, we discovered more fresh holes; and inside there were numerous tiny worms and bugs. We crossed them out in a Book and positive results were "Pine Bark Beetles"! How or where they originated is somewhat of a mystery, but end result is they went with the cut up tree to a burn pile!
Thanks to all who responded..