10 month old STTN

My LO is 10 months old, and goes to my mother in laws house 4 days a week for about 4 hours at a time. Usually he sleeps through the night. I have been out of work for a couple of weeks now, and every since he’s been staying home with me all day, he’s been waking up at night.

On days that he goes to my MIL, he takes a good nap in the morning and does not nap while he is there at all. He also eats a ton while he is there. I have tried keeping him up and not giving him a nap in the afternoon (that was a shit show, never again), and I’ve also tried feeding him more. But I don’t think he’s waking up because he’s hungry, because I don’t even have to feed him when he wakes up. Just pick him up.

My only other thought is that there is a 3 year old who lives with them, and they play together and that wears him out. But sometimes he is not there, and my LO will still sleep through the night.

I just don’t understand. I feel like such a bad mom that my son doesn’t sleep through the night unless he has been to his grandmas that day. Help please 😔

For example, tonight he woke up and it took me 2 hours to get him back to sleep 😭