I honestly do not think emotions in a dog can cause terrible bad breath -do you?
The cause is likely to be either...bad teeth, or teeth so gunged-up with plaque and even tartar, that it is causing inflammation and infection in the gums....or....a digestive problem of some kind.
I think especially as your dog is restless (which means he doesn't feel right) -you should take him to be checked over at the vet's. The vet will no doubt start with examining his mouth. My instinct is that the problem lies there. Probably the vet will suggest a proper scale-and-polish teeth-cleaning. This is a routine procedure, usually with no problems. It is also possible some teeth may need to be extracted? Probably not, but only the vet will be able to say whether that has to be done or not.
Hopefully, that will solve the problem. If it isn't his teeth, then the vet will have to investigate further.
Ginger899 is right, take your dog to the vet for a dental checkup. Our dog had bad breath, and had to have two teeth pulled, even though she had had previous dental checkups. Your dog is in pain, and that is why he is restless.
Hi - I have recently experienced this with my 5 yr old rescue.
We moved house about a month ago and he was becoming really naughty - chewing things when we left him on his own for a couple of hours. Something he has never done before.
One thing the vet prescribed for me was a plug in diffuser which releases a hormone which remins the dog of being with there young mother. It seems to have calmed him down quite a lot, as they felt he had been a bit 'stressed out!'.
Regarding the bad breath - have you tried all the usual charcoal biscuits sometimes its just they need something to chew on and clean there teeth. Your Vet will be able to advise you further. Good Luck.