one or two days not eating in a new environment would be considered normal and nothing to worry about. stress can also sometimes cause vomiting. but i seriously think you ahjould have this pup checked out by your vet as soon as is possible. it may be nothing but it may be something and if it is something the longer you wait could prove very serious for the dog. just for an example he could have eaten something like a toy, underwear, anything and it could be causing a blockage. the longer you wait the bigger risk of doing serious damage to intestines etc. just an example.
i totally agree with scout ! have the vet do a thorough check-up . that way you can rule out any physical problems first. i have two french bulldogs, but i also have a german shepherd . he's nine years old and i,ve had him since he was eight weeks. the first couple days we had him ,he didnt want to eat and seemed "depressed" we took him right to our vet and he had parvo. he spent a week at the vet on ivs, but survived due mostly to early detection. i'm not saying that is what is wrong in your dogs case, but early detection of any disease is always the best for a complete recovery. it sure saved our harley, who by the way has grown into a beautiful and healthy boy !