In the U.S., there are no oral antibiotics sold over the counter, without a Rx. Any chance you get get one from your vet/have him examined? As for the cranberry juice question. It does have some bacteriostatic properties; that is, drinking it has been found to PREVENT UTI's but it does nothing to TREAT an active infection (won't kill the bacteria) other than helping to flush the urinary tract, the same as drinking any other fluid would. If you can't get him to the vet, I would definitely try and encourage him to take in as much fluids as you can get him to drink. I'm so sorry that Frisco's had such difficulties. I'll be keeping him in my prayers.