Oh, Stacie, I'm so sorry for poor Smudgie.
When Baby died, Mr. Whiskers was just not himself for a good long time. He didn't eat much, wouldn't run on his wheel, he just laid there with his little head on his paws hanging over the edge of the cuddle cup that he used to share with Baby. I spent a lot of time sitting beside the cage with him and crying, both of us grieving in our own way. I hand fed him pellets and pieces of hay.
I know that Hedgemom always says that "Chinchillas are not teeny tiny humans in fur coats", and I know that I really tend to anthropomorphize my chinnies, but I'm certain that animals get depressed just as we humans do when they lose a loved one, regardless of the circumstances surrouding said loss.
Just give Smudge lots of love and attention, and I think he'll eventually come around. The boys and I send our love and whisker kisses.