A.T.
You have a ten week old so to your terrier, this is still a new thing. He is nervous and doesn't know what to make of it. When you came home with the baby, did you introduce baby #1 to canine baby #1? It's great that you let him into the nursery. Keep a close eye, but let your terrier get accustomed to the new surroundings and atmosphere. Once baby #1 is asleep, don't forget to cuddle canine baby and let him know it's ok. You might want to give your terrier a less used baby blanket with baby's scent on it so he can familiarize himself to the new addition.