Nausea & vomiting a week after Brazilian Butt Lift, is this normal ?

Its normal to feel nausea after the Brazilian Butt lift surgery, its normally produced by the anesthesia.

Nothing about what you are describing is "normal". It is best for you to contact your PS immediately to discuss your symptoms since they are familiar with your medical history, surgery, and type of anesthesia. You want to make sure that something more serious is not going on. I have had patients develop nausea and loss of appetite secondary to severe constipation, which can be caused by the narcotic pain medication if the patient is not taking their stool softener and drinking plenty of water. Narcotic pain medication itself can also cause nausea.

It is best to discuss this with your surgeon. Asking advise about this online is not the appropriate path of you to get an answer. Or, you need to be seen in person.  Good luck.