I think a squirrel probably. Sounds too big to be a mouse. Too small for anything else. Could be a rat I guess, but I think squirrel more likely. So I'll have to figure out how he got in my walls. But it's driving me crazy making noises directly under me. MFSquirrel!
It's kinda cold here. I'm afraid the heat might draw more.
Start a fire. Should get any animals to run out of your home.