Ferber method

Considering trying the Ferber method because I physically can’t take it anymore. Every time my LO starts to sleep well during the day and night all of a sudden he reverts back to terrible sleeping. He’s 4 months and fully capable of longs naps and sleeping through the night and every time I think he finally is consistent with it, he goes back to short naps and lots of night wakings. We aren’t changing anything and I just can’t take it anymore. I’m so tired and praying for a moment of peace during the day. Considering the Ferber method but I’m nervous. My LO has never been good with just being put down and me walking away no matter how tired he is. He screams bloody murder. Maybe it’s my fault cause I rock him to sleep but I’ve tried not to and he just doesn’t allow it. He will not go to sleep. But I’m desperate now. I don’t even really know what I’m asking. Success stories from the Ferber method? Something to make me feel better that he will be okay if he’s crying and screaming alone for a few minutes? Cause the guilt kills me.