My LO is 4 months next week. Up until the past 2 weeks he has been sleeping really well, we've had the same bed time routine since he was 4 weeks old (even if he didn't follow it then lol). He has a bath around 8, a bottle usually 7/8oz, then goes down in his next to me crib and sleeps 8.30-4.30, woke for a feed, then went back down until 8am(ish). But over the past two weeks he has followed the start of his bedtime routine, asleep for 8.30, then up again at 12,3,5ish then up for the day at 7.30! This is killing me! Me and my partner are constantly at each other's throats because of it because it's so new to us! Just need some advice. Don't know whether we need to change our bedtime routine? About a week ago we moved him onto hungrier baby milk to see if it filled him more but made no difference! At every wake up he drinks a good 6oz of milk so clearly needs it! I'm new to mums net and limited to people to talk to about it so I'm struggling! Does anyone have any advice or stories of surviving sleep regression? Thank you! P.s sorry if this message doesn't make sense! I'm tired! 
xx