Help me I’m dying from lack of sleep 😭😑

My LO puts himself to sleep for bedtime and naps. We have a good bedtime routine and he always goes right to sleep when laid down. (Sleep trained since 4m) but now he has been waking at 12am and 3am for about a month and a half and I’m dying. He will not CIO at those times for some reason. Last time we tried he cried for 45min and the whole house was awake so i just went and got him. I just can’t let him cry that long when his room is beside his brothers room. He wakes at 6-7 up for 2 hours and naps for 2 hours up for 3 hours then naps for an hour and is up til bedtime at 7. Any advise as to how to cut those night wakes???