Sounds like something's wrong with the soil underneath. Continue to water like crazy, but also consider:
1. Testing the soil under the sod for too much acidity. You can use a topical application of alkaline lime - natural - to correct.
2. Talk to folks at your local garden center or the place you got the sod, and don't stop talking to them until you have a couple good leads on what might be wrong and what to do about it.
Good luck!
-Ivy
Parenting two active, wonderful boys
This is your world. Shape it or someone else will. -Gary Lew