Tips to get in routine?

As

I had my son on a schedule and routine for a couple of weeks, but I got sick last week and decided to have him spend the night at my moms. I don’t know what his deal was (not the first time he’s stayed overnight there) but he stayed up all night while he was there and now he’s stuck on it. I’ve tried everything to get him back on his old schedule but he just refuses. I’ll have him bathed and fed at around 8 and he normally goes to sleep then but around 10:30 he’ll wake up and refuse to sleep until 4am. I’ll even try and wake him up early and keep him awake most of the day but still doesnt work. I need help! I’m exhausted from staying up all night with him and I’m getting absolutely nothing done 😩