sneaky secret cheese sandwich

My bedroom smells like sandwich. I don’t know why. I keep it relatively clean, and I’d like to think that I am clean, yet the smell of sandwich often rears its ugly head. It doesn’t always smell of sandwich, but just about 4 days a week on average I walk in there and it is a distinctive smell, sometimes ham sandwich, sometimes cheese. I just can’t work it out (why the smell is there not what the filling of the sandwich is… I can always tell if it’s veering more toward cheese than ham). I started to believe that there was a cheese sandwich hidden in my room, but I’ve looked and I can’t find one. The only remaining option quite clearly is that there is an invisible cheese sandwich somewhere in my room. The problem with invisible cheese sandwiches (and invisible things more generally) is that they are pretty tricky to find. I could follow the smell but it seems to be the entire room. It would also appear that someone moves the invisible sandwich, since it isn’t there every single day. Who is doing this? I don’t know. I just don’t know.