Sleep regression?

My baby usually is pretty great. The last two nights it has been hell. She will fall asleep and then grunt and wake up and just do that throughout the night so exhausting. Its to the point I want to let her cry it out because I am getting frustrated. Usually I can put her to bed at 5 and she will maybe wake up at 9 . Yesterday it took three hours to get her to sleep for some consecutive time. Then she was up grunting and talking. -.- she was acting so tired at 4 and we got her read for bed since yesterday was awful. 20 mins later she is up and acting the same way. #ugh

She just turned 4 months