Welcome to the forum. If she is lactating she has either just had a litter, is heavily pregnant or is experiencing a phantom pregnancy.
Is it possible she had puppies but the previous owner didn't tell you?
She might be pregnant with only one puppy, single pups don't always make the bitch look pregnant, especially is she is a larger Chi.
If she was in season (heat) about 9 weeks ago and is definitely not pregnant then she may be having a phantom pregnancy.
You need to speak to the previous owner to confirm when her last season was. If there is a chance she could be pregnant, (it can happen in a few seconds) you need to get her checked by a vet ASAP. A bitch only has milk in the last week of her pregnancy, so if she is pregnant she is due very soon.
Offer her several small meals a day. She may not be eating due to the stress of moving. If she is pregnant it is vital that she eats. Good luck.