4yo tantrums in middle of night/sudden behaviour change

[beigey]

Hi
Our DS has previously been a deep sleeper and was especially relaxed and well behaved over Xmas. Then BAM! From 1 January he has started having big tantrums even waking in the night with them. Generally the tantrums are about "I don't know what to do/eat etc" or "I can't (get up off floor/put pants on/move)". Can deal with this just about in the day but he is waking in the night, shouting and crying and not going back to sleep. Complicated by the fact this wakes his 1yo sister. Once he was awake 3 hours and last night just kept waking.
Example:
Last night he woke at 12.30. I went to him and he was half way down his bed, no duvet. So I encouraged him to move back to his pillow. " I can't " #whingey voice#. So I lifted him up the bed. "You hurted me" #starts shouting# and he throws himself across the bed. This carries on in a cycle until he is yelling and I'm shushing him because he is about to wake the baby. I give up before I yell back at him and fetch OH who ends up 'sleeping' in with DS most of the night. DS regularly wakes, shouting.

Why has he started doing this? There has been no change in his routine/life coinciding with when this started. We have been a big lax with fruit and veg over Xmas - could it be lack of vitamins? Unfortunately he has also got picky about food (copying baby sister?).
We are trying hard not to fuel his fire by shouting at him but it's hard! He is so angry and unreasonable. He won't let me hug him during tantrums.
I don't think these are night terrors as he is fully aware of what he's doing - although he doesn't remember in the morning.

Any ideas pleeeeeaaaase?

First of all he is only four. Please don't shout at him as he is already frightened. If you were frightened would it help you to be shouted at ?

He is distressed. Maybe something has changed at Pre School. If you haven't mentioned the situation at Nursery or Pre School perhaps you should.
You need to show a lot of love and patience. I know it is hard and it's a b haven't your sleep disturbed! but your son only has one childhood and every act of kindness and patience you display towards him will be repaid in shed loads when he gets older.
Children may not remember the words or scenario but they do remember the warmth.
Please be patient, reassure him with love. When you are old and frail and need his help, he will repay you in kind.

Are you sure he isn't having night mares or bad dreams. Small children do find it hard to put into words route feeling and it often seems to come out in what we see as bad behavior.
Rather then asking if he remembers what happen in the night ask him how he felt.
As op said he sounds like he needs cuddles and reassurance. Maybe Christmas unsettled him, mine have both found it hard at this age going back to nursery after the holidays. All the excitement has worn off. It's easy to think they are more mature then they are at this age.