My ds is 27 months. Since very early on he has always been an excellent sleeper, never really had any of the sleep regressions that are expected. Only things that have upset our routine have been illnesses. Bedtime routine has been the same since 5/6 months and is: 5-5:30 tea, play/youtube until 6:20 (bath twice a week), 6:20 ITNG, 6:50 story and sleep. He has a nap at nursery 12:30-2pm and is generally pretty tired and ready for bed. We get up at 6am to leave for work/nursery at 6:30.
The last couple of months he's been waking up anywhere between 4:30 and 5:30 am (if we're lucky). He's wide awake and ready for the day but then falls asleep in the car on the way to nursery. The staff have mentioned several times to me how tired he is in the day. There's been lots of days where he falls asleep in his lunch or doesn't even make it that far and falls asleep at 10 or 11am. He obviously still needs all that sleep so why wont he stay in bed in the morning rather than drop off in the day?
We bought a gro clock but its not worked. I had to hot glue the power cable in as he kept unplugging to reset it and make the sun come up when he wanted. Now he just ignores it.
The last week or so things have deteriorated further. He's now messing about at bedtime and seems to be scared of going to sleep on his own. He keeps getting out of bed so I keep putting him back. I've had to sit rubbing his hair some nights to get him to sleep. He's also started waking up in the middle of the night crying/screaming. Like genuinely distressed and scared. A quick cuddle and generally he will go back to sleep. It's just so exhausting! I'm working full time and also in my first trimester which is taking its toll too.
Can anyone please help or I'm going to loose my sanity soon 
Sorry for the long rambling post!