Okay, advice needed.

My sweet 4.5 month old is a holy terror at night. For the last 2.5 weeks she has not slept more than 1 hour at a time. 😟 During the day, she is a champion sleeper. Naps are super easy & she is put down drowsy but awake & puts herself to sleep with no fuss. If she hears a noise & is woken up (I also have a 2 year old), she will even put herself back to sleep. She naps for 1.5-2.5 hrs every 2 hours. She is currently in a sleep sack swaddle (when 4 month regression hit she suddenly needed her arms swaddled again. I will be working on getting her out of the swaddle soon) & has white noise playing. She still sleeps in our room (in a bassinet thing) & has a bedtime routine. For whatever reason, she will not stay asleep at night & will only go back to bed if I bf her. I'm exhausted & at a loss as to why this is happening. Any advice is welcome!

Thanks!