Call and ask to speak to the doctor. When your speak to the doctor explain to him your situation and ask if he could at least give you enough pain medication to get you through until the drug test comes back. If he does not give your a prescription than I suppose you should go back to your other doctor. If your other doctor can, (it may be easier) have him to call and speak to your new doctor to explain your prior treatments. Again I urege you to speak to a medical malpractice lawyer. Some have 800 numbers and allow you to get information and speak a lawyer about your case.
Good Luck,
Dr. Anonymous1