Question
Last summer we laid 4 inches of topsoil and Bermuda 419 sod.  It turned out beautiful althoug it stayed a little too long.  At the beginning of this season we cut it to its preferred height and it seemed to be doing okay.  We've kept it cut.  Now it is thinning, yellowing/browning, and just looks horrible. I have looked online and the closest thing it looks like is nematodes.  It could be brown patch but there are no perfect circles and it seems to be an all over thing.     I really don't want to loose this yard and I'm not sure how to find out exactly what is wrong or how to fix it.  Thank you.

Answer
Proper diagnosis is key in any turf problem.  I recommend that you contact your local ag agent to arrange a turf analysis, to include tissue, soil and pest.
Nematodes do cause problems, but I have seen a turf farm with high populations of nematodes and little turf damage.
It could be a grub or fungal problem, but, without testing results, it would be difficult to say.
Best of luck.