My cat seems sick....?

You NEED to get her to the vet, maybe even a different vet. YES I went through the same situation 3 separate times. Cats EASILY get sick and can die VERY quickly. Although some medicines do tend to make cats lethargic, I would take her in. Also there are cat foods that help prevent uti infections, and I'm sure those would help. You have to keep those fluids in her! If when she went to the vet, they gave her an anesthetic, that might be why she is so slow. It usually takes about a day and a half to wear off. ALSO, antibiotics can get rid of both BAD and GOOD bacteria. So you can feed her some PLAIN, no preservatives yogurt. Yogurt has enzymes that help restore the good bacteria into the body. Keep a VERY close eye on her. My grandpas cats have mostly lived to at least 18 years, the oldest was 24! Don't listen to that first answer!