How long have you been in the new place? Chihuahuas can be high strung and nervous by nature. We have a Chi mix that hates the car! For long trips, she gets a bit of a sedative. Your dog is probably stressed with the car ride, moving, new place, and no other dogs he had bonded with. Make sure you try to set new routines and try to stick to them. Reassure him but don't coddle him. Is he alone during the day or are you with him? Try some small meals of chicken and rice and see if he will eat that. If this continues for too long, seeing a Vet may be a good idea. I have never tried it but many swear by lavender oil in a diffuser.