Hello!I had the same thing happen to me with Ativan!It saved my life!It all the sudden stopped working for me. I had to switch to Klonopin. Also, with Xanax, the lowest dose worked forever for me. Then my anxiety got SO bad, it just wouldn't knock the tiniest bit of my anxiety. The gave me 5 days worth of a higher dose til my dr got back from vacation. It helped majorly, just by kicking it up a notch. But they didn't want me on the xanax at a higher dose, so switched me to the Ativan. Maybe it's as simple as switching to something different?
Hope you find relief soon!Anxiety is not fun to deal with

Hugs,
Amber