oh how I feel your frustration.. Although Jacob has just started coming good.. I am finding his lack of sleep was the biggest cause of his problems.. Since he no longer day naps some days are worse then others.

Yesterday I "made" him have a day sleep and he slept 13 hours overnigth and has been awesome today...

So my suggesstion is to get on top of his sleeping if you have noticed he is sleepong less..