Sorry about the questions

Natalie

First time mum and my baby is 17 weeks. I have 2 questions. My son use to be so good at sleeping at night, now his a nightmare and wake up at 1 and then about 4 but then stays awake for like 2 hours! How can i stop this? Also I want to make sure my baby is developing at the right stage what can I do? What should he be doing?