Very cranky toddler

Last night, we went to a New Year's Eve party downtown with the kids. They had a great time dancing and running around. We left around 10pm so the kids wouldn't be in bed too late. Our son woke up several times during the night and when he did sleep, it was a very "fitful" sleep and he was moving his arms around. Today, he was in a crabby mood all day long. He usually has typical toddler moods, but today was much worse. He hardly took a nap, and then fell asleep in his stroller during our walk. But then when we woke him up he was in the worst mood ever and could not stop crying and wouldn't tell me what he wanted or what was hurting him.

Tonight is the same story. It took an hour and a half for him to fall asleep and he is awake crying again now after only two hours. It's going to be a very long night...