3-4 MO suddenly turned into a poor sleeper

[HanSpan1]

Evening all,
My DD1 will be 4MO in 9 days, (but she was 2 weeks late if that helps), and up until a week ago would sleep generally ok in her next to me crib, wake 1 or 2 times in the night for a quick feed (EBF), then straight back to sleep. However, since a week ago she will go down in her crib anwhere between 8-10PM and wake 20 mins late crying, after another 20-30 mins on the boob she goes back to sleep and we transfer to crib, rinse and repeat waking every 20 mins or so,
We even tried introducing a dummy but she just chucks it out after a few mins and cries,

The only thing that works (which I begrudge) is co-sleeping, it seems to be the only way to get her to go to sleep for longer with maybe 2 feeds in the night. Does anyone have any advice??? Or similar experiences?? My poor DH goes in the spare room to give us a bit more space in the bed, and he worries he might s quash her in his sleep.

Other things worth a mention, since the last month, she salivates ALOT, always has her thumbs in her mouth, and her poo’s seems quite runny/watery.

Thanks all.

Google the 4 month sleep regression 😣 my two were horrific with it. We Co slept and it was the only thing that saved me from going insane! Hopefully it doesn't last too long for you!
Also the drool and the thumbs is all totally normal she might be teething or she might of just found her hands and likes them in her mouth. Wait until literally everything they get their hands on goes right up to the mouth 😅

Sounds normal. My almost 13month old still does something similar.
Sleep is not linear it’s very variable