Hi,
I too had a bunny with a bladder stone. Unfortunately we had to have her put down as we couldn't go through with the operation to remove the stone, and she deteriorated very rapidly one night.
My bunny, Dee, first presented with severe stomach pain and we ended up rushing her to the vets at 11pm one night! She had loads of tests etc as well as a single conscious x-ray (she was in too much pain to move, bless her) and then, when she was well enough, she was x-rayed again under GA. This revealed a 'thickening' in the bladder. She was put on various meds such as metacam, septrin, cerina and tramadol, and this definitely helped her. She picked up and was doing really, really well. Unfortunately, however, the stone then moved, about five weeks later, and this was what caused the next onset of pain - much, much worse and too much for her in the end. The vet could actually feel the stone when it moved, hence how we knew what it was.
I don't want this to put you off or anything, though - I have no doubt that, had she have the operation, she would have made a full recovery. It just wasn't right for her to have the operation. She was old and frail, as well as small, and I could tell she'd given up.
Hope your bunny is OK!