For the last week, he has been going to lie between my couch and the wall as if hiding away. This is out of character. It’s as though he goes into a depression for a short while then comes out again to play. He is eating and drinking normally and doesn’t seem to have any physical problems. The only change in the house is, my mom has come to stay with me. She has inoperable cancer and she’s staying with me to look after and keep her comfortable. Would this affect my dog because i’m sure he can sense how ill she is? Would there be any other explanations for this behaviour?