Babies sharing a room, younger baby won’t sleep

[u/AlarmingAvocado2509]

Kind of at a loss for what could be keeping my 7 month old up at night.

Because of where we are renting, our 2u2 share a room. They nap perfectly together during the day and have even slept full nights together without waking each other. The younger one outgrew the bassinet in our room and we decided it was time for the crib, and I would sleep better if I wasn’t nursing all night. Also had almost fully daytime weaned baby until recently it seems like a regression and lots of biting while nursing. Now, he’s up 3x a night just screaming, won’t take a bottle at daycare or home, and really to me his screaming sounds like overtired or maybe pain. He was a really decent sleeper until now. For context, my older one didn’t sleep through the night until like 14 months old, when I had just given birth the second time.

I’m not sure if it’s teething, tummy aches from formula now that he was almost weaned, or something else I’m missing. Tried gas drops and Tylenol but he still screams like he’s uncomfortable. Thinking about buying a new formula. I was even okay to let him safely sleep with me if it would calm him down but he doesn’t want that either. My partner and I take turns so we’re not totally sleep deprived. What am I missing? Or it is just baby being baby?

[u/Front-Cantaloupe6080]

we found two pillows in different colors, but putting them in the same bed. worked great