Great question, Karen! This is quite a complex subject and we'd love to provide you with the best info and advice available. May I suggest a virtual consultation with one of our experienced veterinarians? They can offer tailored advice on antibiotics and the best diets for your cat from the comfort of your couch. You can view our vets’ availability and book a time that works for you: www.pangovet.com/?Catster&RU-vid&
A probiotic such as fortiflora is what my vet suggested when my cat was on antibiotics. Proboitic 8 plus is a good one too. Fortiflora is the vet reccomended one, when I saw a nutritionist for my cat she said Alpha Omega(maker of proboitic 8 plus) is a really good brand. A call to your vet's office may gain some good info as well, often the receptionists are quite knowledgeable!