Please take the cat back to the vet. We are a design website (we make things pretty), not a veterinary college. There is nothing we can/should help with.

Hi Fafa, So sorry to hear about your Snoopy. Awful to see a pet suffering and sick. I am no vet, but here's a site I like to use for natural pet remedies because as you and many others have experienced, vets and doctors don't always get it right or their methods don't work. http://www.earthclinic.com/pets/cats-urinary-tract-infections.html
Don't know if that will be of help to your cat's situation. Hope he's doing better already, and if not, hope some of the reader advice there will help. Also be leery of the vet prescribed food. I know another user on here mentioning her cat having some kind of urinary problems and the vet prescribed a special food that made him really ill. I'll see if I can tag her over here to your thread. Maybe she can share what she did for her cat who is one hilarious, beautiful goofball with the perfect name to fit. Sending get well wishes to you and Snoopy.

hey there, so sorry to hear about your cat. i know just how you feel, my cat got blocked too. after he was unblocked, he was def not himself for a week or maybe two. he spent a LOT of time in the litter box still and just acted very sickly. but he did come around. i am the person swrite mentioned about the vet prescribed food not working. thats not exactly what happened, the food worked for the urinary blockage, it did not return, but the food made him very obese, he developed terrible flaky and dry coat and he somehow developed asthma! i believe he would have become diabetic if we kept him on that food. anyway long story short, we did our research and decided to take him off the prescription dry food and feed him a good quality wet food, and only wet food. we dont feed him any fish based food due to its higher phosphorous content. the"natural approach theory" basically states that cats do not drink enough water to keep their system clear, rather they get their water from their food and dry food doesnt give them the water they need. my cat has been on wet food only for a long time now and not only did the blockage not return but he looks so healthy and is so happy. his asthma disappeared, his coat is shiny, he has tons of energy and lost all the extra weight. if you decide to take this approach PLEASE do your research first, i dont want to say this IS THE answer for your cat, i just know it has worked for mine. i wish you and snoopy luck.