I live in north central Texas. My Red Oak Tree has been sickly for the past few years. After much reading, some from this forum, I diagnosed that it was planted too deeply. So, I've lowered the soil level around the tree to expose the root crown. There were sucker roots coming out of the top of the crown roots so I cut them back. It's been 2 months and my tree doesn't appear to be getting any better. There is still brown edges on the leaves and dark spots on the trunk. In fact it may be getting worse. Any thoughts?