I am sorry to hear you are worried about Cadbury. My name is Rebecca. I am a veterinarian and will do my best to help.
Is he having diarrhea at all, or is the stool unusually hard or dry? The first thing is to be sure this is not a physical problem that needs treating.
If he is negative for parasites and the stool is normal consistency, then I would confine him at night in a crate or small room. He must not be allowed into the area where he has these bowel movement at night, or he will just keep doing it. To change a dog's behavior, they learn by you being proactive, preventing the unwanted behavior, not by your just reacting to feces in the house. He may need to be crated or confined at night, until he learns again to make it through the night without defecating.
First take a stool sample to your vet for checking, or if he has diarrhea, have him checked out to find out why. If he has soft or loose stool, he may not be able to help himself, he may not be able to make it through the night without defecating.
Let me know what other questions you have and if this is helpful. Rebecca