Does your 2 year old wake up after sleeping 3 hours crying non stop? How do you distinguish if he's having a nightmare?

Any change in routine? Did your little one recently come back from a holiday? Try having him co sleep with you for a little while. My lo was like that when we moved him to a new bed.He was totally happy in the day, but obviously internally he must have felt unsettled and that came through in unsettled sleep at night.