My male cat has gone through 2 weeks of Clavamox and didn't get well. I've taken him back to the vet twice. She said he wasn't blocked and just to wait and see. I go nervous and took him one more time. She doesn't seem to think there is much more we can do that what we have. I told her that I had read all this and she said it's worth trying. I've had him on either 1/4 Apple Cider Vinegar to 1 tsp water or 1/2 to 2 tsp mixed in with a little food 3 times a day for a week. I'm always for natural healing and not a skeptic, but I have seen zero improvement. He is now peeing a small stripe instead of small dots, but I think that would happen with time anyway. His frequency to the litter box is the same.
Just don't get your hopes up from all these "He peed a river after the first dose! " reports.