MOTN screaming

Baby boy is 18.5 month old, going through a sleep regression and separation anxiety since mid May, so it’s been like 3 weeks now. He’s always been a great sleeper, falling asleep and settling himself.

I noticed when he started with sleep regression, he completely stopped sucking his thumb and was also fighting off an illness. Even after he recovered, his wakes and screams got worse.

On some nights he’ll wake up once, on other a few times, but the most common time is around 3-5am. I tried doing CIO but he’ll just cry until he’s exhausted and pass out (also wakes my 4 year old). I tried going in to carry him briefly, but he won’t want to me to go and would still escalate. I tried the chair method, it worked as he drifted off to sleep but will wake up screaming again to see I’m gone.

I am absolutely lost.

Schedule: wake 7/7.30am, nap 12.30/1pm to 2.30pm, bedtime 7.30pm

I would push wake time to 7.30/8am if he had a rough night and for me to catch up a bit as well.