Best is to take her to the vet to check that out -The Urine test, etc etc ..
I understand money is involved but she needs your help! if medical is cleared -- Best to confide her to one room (no carpet!) for a while or even in a crate. Take her out often. It could be a small bladder. Or Your dog may be untrained before she was sent to your home. Take away a bowl of water at nite. While taking out for bathroom outside. When she does it .. Best give her good praises .. For ex. Good Girl, give a dog cookie, etc etc. Again never scold or spank at your little pup (even she has an accident in the houes)! Take her out immediately! Take alot of patience! Small like Chihuahua and possible a Mexican Hairless dog tend to be very nervous and anxious. Not worth to scold at her with a high or angry voice. Sorry I am not a veterianian or a pet therapist. I've worked at the vet hospital for 6 years as a technican.
How interesting .. Did they provide a very little information on your dog's medical history before she was shipped to your home? How long ago is that? What breed is that? And...... you forgot to mention her name! She is sooo cute!