Toddler suddenly screaming at bedtime. Please help! So lost

Hey everyone. I really need some help and insights please. My 19 month old daughter has been a great sleeper since she turned one. We have a solid bedtime routine, I put her down awake, and she rolls over and goes to sleep. Same with naps. A week ago everything changed. Now she is absolutely screaming and crying “Mommy!” on repeat until I go back in. I’m not a huge fan of CIO. I have a 15-20 min absolute tops limit. It’s just so hard on me. I’ve tried giving her 20 mins or so, I’ve tried to go in and reassure with no luck. The only thing that works is rocking her to sleep and I don’t want to continue. What should I do?! It’s separation anxiety. She wakes up during the night and I hear her say “Mommy!” In a panicked voice but can usually go back to sleep. Does anyone have any ideas?? Thanks in advance!