My four month has never been the greatest sleeper but hasn't been terrible, would wake every three hours. Since Sunday I don't know what's happened! She has been up the whole night just screaming! She is hysterically screaming. I can't cope. I've not slept. I live in a flat and have two other children who are shattered bless them. I rock her she screams, i feed her she screams, I change her she screams, I don't know to do. She just won't stop screaming. Please someone have some advice.