First, trees never need fertilizer unless they are missing a specific nutrient. Fertilizer will make a tree put on growth but will not make it healthy, unless it is missing some nutrient, which is highly unlikely. Second randomly treating is more likely to do harm than good. We need more pictures and information. Watering well, what does that mean? Twice a day for a few minuets with a hose, a good way to kill a tree? Or once a week long and slow and deep, which is correct. Can you see a distinctive root flare at the base, preferably with the tops of the first major roots showing, or does the tree enter the ground like a telephone pole? Is there mulch half way up the trunk?
The lower leaves look OK, answer more questions and take a picture of how it was planted and we may be able to help.
Google "10 fun and easy ways to kill your trees" to see if any of these things match your situation.

I water deeply approximately once per week. Again, the tree has thrived for the four years since I planted it (it put on ~12-16" of growth last year!). I'm a little shocked since I thought I watered so well but I think I failed and the tree is suffering from scorch and I assume borers (although I can't see any holes). We set record high temp after record high temp this year - this was the third hottest summer ever in our area. The tree is planted correctly; the root collar is at soil level. The tree does not sit in a "bowl" and it is located on a slight slope with good durface drainage (~1/4" per foot). The tree is not mulched; it competes with lawn grass. The soil is crap; the tree is located on an old building site with much buried rubble. I have been flooding the area with water for the past two weeks and the tree looks no different (better or worse). I've attached a pic of the weeping trunk.