Our DS (5 months) is doing a very similar thing at the moment. He used to go down really well at about 6pm and stay in bed until about 1 am for a feed and then he would wake at 5 am. That's all completely gone out the window now and I'm not sure why. We've started giving him some rice cereal to see if that helps but it hasn't. Everyone I talk to pretty much saya I need to start control crying him to sleep because he has bad sleep associations (ie. dummy, rocking, feeding, etc). I'm really nervous about doing this but thought I would give it a go as I'm massively sleep deprived as well and not really coping during the day. I wish we didn't have to do it but our DS doesn't seem to know how to resettle himself at nighttime so we have to give it a go I guess. Hope you find something that works and if you do can you let me know?