Hi folks, looking for some solidarity or guidance on anyone who has tried sleep training their toddler.

Our son was sleep trained and a pretty good sleeper since about 4 mos. He's hit every regression but usually with a few days of checking/CIO, he figures it out and goes back to sleeping through the night.

A few weeks ago, our toddler was accidentally locked in the car by his grandparents. He was totally fine, only in there for about 5-7 min but he was scared when they had to break the glass to get him out. Before this night he was an amazing sleeper, 7:30-6am, fell asleep independently (even in new/different spots) and slept through the night.

Since that night, he's been waking up screaming. At first we thought he was scared so we went in and comforted. He started refusing bed times which he's never done, so we stayed in the room to help him to sleep. It's now been 3 weeks and every day just gets worse with more MOTN wake ups and even harder bed time/nap refusal. He's not anxious/scared during the day of the car, or even of us leaving, so we think we've just created some bad habits and this is a regression triggered by the car incident.

Last week we tried CIO both gradual and full, for a few nights - on night 2 he calmed down quickly but stayed standing for 2 hours so we caved. For night 3, we tried moving him to a pack and play and he flipped out so we caved again. We've paused but things are just getting worse and now we think he's gotten used to all the comfort. His sleep sucks because he wakes up multiple times a night and takes awhile to get back to sleep.

We know he can do it and he likes to sleep independently - he used to be a happy, confident sleeper. Talked/sang/played to sleep, woke up happy. Now he's crying and refusing sleep for naps, bed time and MOTN.

We've tried gradual extinction but the checks seem to make things worse for him and he has to resettle. Anyone been through anything like this and came out on the other side? What did you do and how long did it take?