Did any of your toddlers go through somewhat-major sleep regressions?

J is 17 months. He has in general been a great sleeper most of his life and has been fully STTN since 11.5 months.

But the past couple weeks, he fights going to sleep so badly we have to go in to soothe and comfort him 5+ times between 8-9pm. Then he has at least one night waking anytime between 12-4am, and then is up between 5-6am crying. Today he was up from 4:30-5:45am and no amount of rocking, soothing, giving his pacifier would get him to go back to sleep until about 6am. Then of course he slept til nearly 9a,m

It's getting pretty tough and I'm not sure how to do things differently than I am... I'm hoping it's just a phase and he will outgrow it.

He cries when he wakes up but is fine the moment we pick him up, I wonder if he might be having bad dreams? But I have no idea. Grasping at straws here.

Anyone else?