What's Wrong?

Chacha has ate very little the past few days. Other then that, he seems fine. I don't know what is wrong with him. With the cold weather we have been having, he has not been going outside much, so maybe he just ain't hungry. My mom bought a pen a few days ago for him to stay in when I am at work. He always seems to slip out of his sock (he pees inside the house...) and he really don't like the baby my mother has been babysitting (I don't blame him). He does go in the pen by himself sometimes, so he don't hate it. He was eating fine before then, but won't even touch his favorites now.