Advice/Help baby won't sleep anymore.

Hi.

Looking for advice or if anyone has been in same situation when they done.

So my ds is just over 4 months old, he settled in a routine very quick, his doing, would get cranky if jammies aren't on by 7ish, bottle and bed for around 8.30ish, at around 2 months that was him till about 4/5am bottle then back to sleep till around 6.30, in the last 2 weeks or so he's been forcing himself awake at around 10/11, then at 1ish, then 2/3, 4/5 then out day starts at 6, I can see he's tired when he  up at 6. My hv advised not to give him milk as he could get used to it but most times that's all that will send him back to sleep, the odd time it's 5oz but mostly just an oz if that. He's such a happy baby and coming on great, but why has he decided not to sleep? I'm very sleep deprived and fine myself sitting in the couch with no energy even just to put clothes on.

Sorry it's long, hope someone can give advice.

Thanks.