Hello! I Have A Very Frustrating And Difficult Problem That

Hello! I have a very frustrating and difficult problem that I am currently dealing with. I have struggled with addiction for years and am currently a patient at a methadone clinic. I have been on methadone for approximately 5 years and done pretty well except for a few short relapses here and there. On March 7th, I had to have oral surgery and the doctor had to give me versed to sedate me. I showed my paperwork to my clinic, but after my most recent drug screen, I tested positive for benzos and they sent it to be further tested. The benzo test performed did not test for versed or midazolam, but it did come back positive for a-oh-aprazolam. I understand that this is a metabolite of Xanax yet i did not take ANY Xanax. My clinic is forcing me to do an extreme taper due to the fact that I have no prescription for xanax and I fear I will relapse if I can not get this issue resolved and my taper stopped. I paid to have the sample retested but the results came back the same?! Is there any possible reason why I would show up positive for a-oh-aprazolam, when I only took my regular methadone and was given versed and lidocaine for my oral surgery??? I've done some research but can't seem to figure this out and I am extremely frustrated!! My clinic believes that I am lying and did take Xanax, yet in the 5 years there, I've never tested positive for benzodiazaphines ever, I'm not a fan of them!! Plus, if I did take Xanax I would openly admit it, but I did not!! Please help me!! I truly fear for my sobriety and as a recently widowed woman with a one year old son, I have a lot to lose! Thank you for any help or advice anyone could give!!!