So overwhelmed

I'm crying as I write this because I'm so overwhelmed. My four month old will not sleep in the crib tonight. After 2 hours of trying to get her to go to sleep she just cries and wakes herself up after 5-10 mins. She never sleeps great in there but will sleep for 7 hours in her rock and play. I'm trying to be a good mom and make her sleep in her crib but she hates it. I told me ped this and she said to let her cry it out. I tried today and she just kept screaming and it didn't work so I'm not doing it again. I heard of the 4 month sleep regression. I'm so tired and overwhelmed some encouragement would be great right now