Wakes up every night screaming

I'm dying over here. My little guy has always been a great night time sleeper and has slept in his crib since 3 months old. He goes straight to bed no problem in his crib. He's turning 18 months this week and the last 6 nights he wakes up screaming! Absolutely will not soothe himself back to sleep like he always has. Nothing seems to be bothering him (no fever, not really teething, etc). As soon as one of us rushes in and picks him up he's instantly snuggling in and falling back asleep on our shoulder but refuses to go back in his crib until we either rock for hours and try multiple times, or we finally give in and take him to our bed (which we've never done before now). My husband and I have been taking turns so that we get some sleep, but after almost a week of it we're running on empty. I don't know what to do anymore! 😫 Someone please tell me this is a phase that will be over quickly! (Currently up rocking now 😣)