You need to retain an attorney. A motion to revoke is governed by probation. The UA results will go to the court and the PO attched to that court will make the decision whether to file a motion to revoke. An attorney may be able to discuss the matter with the court PO and show him the prescription from your doctor (which it sounds like you have). Normally controlled substances with a prescription for a legitimate medical condition are allowed under probation terms. You also need an attorney to present this defense to the judge should probation decide to file a motion to revoke. If your probation is granted, the judge can decide to impose a sentence ranging from putting you back on probation all the way to imposing the original sentence from when you plead.
I agree with the above response. If you have a prescription there should be no reason you cannot continue on your probation. That said, hire an attorney. The probation department will decide whether to file a motion to revoke but the probation department can seek input from the court- it sounds like that is what is happening here. I wouldn't trust probation to tell the court you have a prescription though. HIre an attorney to be safe and protect yourself.
Hire an attorney to have them work on the issue for you.
This is intended as only general legal advice. Feel to visit my website, www.austincriminaldefenseattorney.com for my blog on crime and punishment in Texas You may also email me through my site.
Provided you hire competent counsel to walk you through this, you should be able to get the MAJ (Motion to Adjudicate) dismissed, and placed back on probation (if the State files a Motion to Adjudicate you in the first place).
The courts around here aren't the most reasonable of places to be charged with a criminal offense, but from the sounds of it (and provided there aren't facts I don't have here) you have a very legitimate reason for failing the UA. In some cases, one dirty UA won't even provoke the filing of a MAJ, but it's not something you want to be caught unawares on. If the State files the Motion, a warrant will be issued for your arrest. Be proactive as much as possible. If your PO isn't responding to you, hire an attorney to go on the offensive, and get the explanatory information before the Court, so that you can avoid as much hassle as possible.
Best of luck.