My daughter is almost 5 months old. We were doing really well with extending naps by pu/pd. It took a while but was worth it. It worked without pu/pd for 3weeks without a problem. She would wake, but very quickly go back to sleep. She would grizzle for a little while, but there was never a need for me to help her go back to sleep. Suddenly this week she refuses to sleep longer than 30/40mins, sometimes 20 minutes. I've tried pu/pd. I don't go straight into her. If she does go back to sleep it is only after crying lots and then wakes up after 10 minutes. She is tired as she is yawning, rubbing her eyes and grumpy within minutes of coming out of her cot, sometimes falling asleep during her next feed, so I have to keep waking her! She isn't hungry, she feeds well. What have i done wrong?She sleeps very well at night, so i feel daft for asking for help. Any advice would be great.....