Not sleeping through the night

My almost 6 month old who was sleeping through the night now wakes up multiple times a night. She goes to bed around 8-8:30pm at night then wakes up crying around 11-12 then wakes up again 3-4ish then I feed her and she will wake up again around 6 for food. Some nights she gets up like once every hour screaming and sometimes I just need to give her the paci. But I’m not understanding why. She used to sleep through the night just fine this have been going on now for about a month. This mama is exhaustedd. She’s eating cereal/purées which should keep her full longer. If you have an advice please let me know!