Hogs frequently don’t use the nice new houses we buy them – or not for a year or so when they don’t smell so new, so just leave your cardboard box. It is possible it has babies in it if it’s stayed with it after you moved it
With regards the hog getting up mid morning. You say it’s small but if it’s last years hog it could be pregnant/nesting, but equally it could be sick and needing intervention, so your safest course of action is to speak to your nearest carer who can get more info than you’ve given here and advise.
Despite all that is said about hogs being solitary, and they are, they will often share a sleeping place both with familial hogs and other non aggressive hogs. We see more of this now as the hogs habitat is shrinking into our gardens so you are getting more concentrations of hogs in one area
