3 year old waking in the night 😩

So my 3 year old for the past 3 days has started waking up at like 2-3am and he will go to his gate and start asking for me, so the first night it was 130am so i go in put him back to bed, ask him whats up (its hard as hes got speech delay) but nothing would be up, ill give him a kiss and cuddle and go back to bed throughout the night hes up and down and up and down so this has gone on for 3 nights now he will go bed about 630pm after his bath and story time and then all of a sudden he will be up at 2-3am i feel like iv trued everything, being nice kisses and cuddles, laid with him, spoke to him to ensure him that hes safe, put him back with out talking to him and just left the room, it gets to 6am when i have to feed the baby and im pissed (i shouldnt be but for 3 hours iv been trying everything) so i end up being firm and just telling him to go back to bed! More like demanding him to do to bed, and sometimes in the night he will literally just lay there wide awake, i dont know what to do, hes even still full on duing the day (he goes to nursery as well) like theres no off button woth him, he will go to sleep fine no problems there but he will wake up in the middle of the night and stays awake then 730am im up with him and baby.

Any advice will be greatful!