Ferret starts not using litter box

Question
Hi so I have had my 5-year-old ferret for about a year now and he has just started to not use his litter box. I have just moved to a hotter city then where I did before but when I moved I still did not have this problem. A about a month ago, I lost my 1 1/2 year ferret to internal injuries and he was his best friend. But this has just started about a week in half to two weeks ago. I know that he has not been feeling good and he is going to the vet tomorrow for a possible diagnoses of ECE where he will get antibiotics but I do not know if this is where this whole problem rooted from. He has a new friend who is a female and they get along famously and she does use the litter box. Please help! Thank You!!!

Answer
It seems there are a few factors that could be influencing his behavior.  First, the change of losing his friend and moving.  The health issue could certainly be a problem.  At his age, I would also check for adrenal as it could be causing a problem too.  If the vet check goes well, give him a little time to adjust to the move and the new friend.