My son would only sleep if he was being held, as soon as he got horizontal for bed he'd be wide awake...It was a tough time.

We had 3 kids at that time ages about 7, 3, 1. And my eldest struggled to sleep also.

What solved it for us was putting two queen mattresses side by aide on the floor and just having the kids all sleep with us.

I understand the Western World often sees this aa a negative solution, but its common in other cultures for kids to sleep in the room as the parents.

The kids felt safe, and parents could doze a bit if the kids were awake, but at least not crying.

Once they got older we moved them back to their bedrooms.