4 month sleep regression

First time mom here so this 4 month sleep regression is no joke ! my baby is 16 weeks and sleep regression started right at 15 weeks .. this past week has been hell. She used to sleep great for a newborn, we had a pretty good routine she would go bed at like 8,9pm then wake up once at 3am then back to sleep until 7. Since last week she barely naps during the day, she’ll nap for maybe an hr at the very most and take 1-2 naps a day so by 4pm she’s cranky and fussy. Bedtime has become the worst it’s harder to get her to stay asleep then before and she literally wakes up every hr it seems.. I feel so bad for her.. How can I help ?