I am having the exact same problems. Except DS2 will go to sleep in my arms and as soon as I put him down he'll be screaming the place down. He is just not getting enough sleep for a little baby. It worries me no end and it's driving me batty. Sometimes he'll sleep ok over night but it's getting to the stage where he is wingey and tired all day and that means I am spending all my time trying to calm him and settle him and DS1 is being ignored. I feel like the worst mother in the world.