It can take 3-4 weeks to get on top of a urinary tract infection but you would like to see some noticeable improvement within a week or two. If there is no response to the antibiotic, then you and your vet may want to consider either another antibiotic, check for problems in the reproductive tract (womb and ovaries) and lastly consider sterile interstitial cystitis (a non-bacterial recurring infection of the walls of the urinary tract - although this usually doesn't come with the kind of smell you are describing).
All the best!