I'm so sorry this happened to you. Labs can make mistakes so your Dr should have called you right away for another test.
She didn't even give you a last prescription? That's not right and it could have been dangerous for you going cold turkey.
Is there anyone above her you can talk to? It sounds like you've been a perfect patient all these years.
Is this a new Dr you were seeing? I'm asking because you mentioned a first urine test? If it was a new Dr it might have something to do with you being on Medicaid.Some Drs don't like to mess with the extra paper work and I think it takes a little longer for them to get payments compared to private insurance.
You need to start making calls right now. See if there's anyone above her you can talk to. If not, call and ask for another test and tell them it's inhumane and possibly dangerous cutting you off of your meds with no last prescription. If they will do nothing contact your primary Dr to explain what happened. Sometimes they will take care of your meds while you're finding another pain Dr. Also, ask your primary if they can recommend another pain Dr. You should have a list of pain Drs who will accept Medicaid so check out that list.
Please keep us up to date on what's going on. If you need more help let us know, okay.