How long do you let your 2 month old cry

Maude • •👼🏼C 💙•H🌈•B🐻

My baby has been awake screaming for 20 hours. She only settles if she’s being fed but is wide awake. She doesn’t have a fever and I’ve done everything. I’m honestly done and I think she might just need to cry but I’m not sure how long is an appropriate time to let her try to settle herself a little.