K.K.
He could have an ear infection and you would not know. My son got them all the time, and never showed symptoms like fever, etc. except that he use to wake up much earlier, and then a few days later start eating less. So I would take him to the pedi and sure enough, ear infection. Also, I think it could be to young for night terrors, but never know. When putting him to sleep for the night try to remind him of the fun things he did that day, so that those memories will be the last thing he's thinking about when he falls to sleep. Also, try not to have the news on, or anything violent during the day that he can see. Those visuals can come back in their dreams.
Good Luck!!