6 month sleep regression!?

He is almost 6 months...JUST this week, he's started fighting sleeps...all sleeps. Used to be, I'd put him in his crib and he'd pass out no problem. I was like, "man, I'm so lucky."

No, he cries for a half hour...even more before falling asleep. Waking up multiple times, can usually get back to sleep himself and ends up sleeping 12+ hours. But geez, dude...is this a thing? My husband literally had safety earphones on because baby was crying (my son hardly ever cries, so my husband apparently doesn't know crying is something all babies end up doing.

But, is that what's going on? He completely skipped the 4 month regression...maybe he's making it up with a vengeance?