Me and my family are pretty close with our neighbors, they live downstairs from us so sometimes their door would be cracked open a little for my cat to go there. He would be there a lot, now all of a sudden he doesn’t go anymore? And he would always stop by the top of the stairs and try to listen for something and he would look kinda scared with his tail down. He doesn’t even want to eat his treats anymore which he would always go crazy for. He’s a very vocal cat but now he doesn’t talk to me as much which concerns me, it always seems like he’s so concerned with downstairs but he never goes in there. There’s an old lady that lives there she’s around 90 something and she lives with a caretaker. Maybe he’s sensing something is wrong? I have no idea, I would take him to the vet but I feel like they wouldn’t understand me