DS gets frustrated sometimes when he is playing, if he cant get a toy around the corner etc, or it gets stuck, and cries and kicks and gets upset. His is not related to sleeping, but if your DS is tired during the day, then it might bepushing hie tolerance thresholds down?

Does he speak a lot? Maybe it will change as he can vocalise more and tell you what the issues are? I've been told that about my son, so I'm hoping its true!