15 week old and sleep- please help

[Blak]

I believe my DD is hitting her 4 month sleep regression, she has been an amazing sleeper up until now, nothing used to wake her and it never took long to settle her at all but now things have completely changed. I was just wondering how long this will last and if anyone has any ways to help her self settle?
Thankyou

I think the worst of it lasted a week, however he didnt go back to sleeping the way he did before the regression happened for a month or two. I actually remember at maybe 5 months old he started feeding 3 x per night again for a week or two before dropping the night feed entirely.