Shih Tzu Sneezing. Meds are not working. Can you help!?

If you are not happy about what's going on, take her back to your vet!! Normally a dog reacts, shows an improvement to antibiotics if they are working, within 48 hours - although of course, you have to complete the course. Your vet will have started her on a treatment (normally the least aggressive) and if this isn't working, he needs to up the treatment. I certainly wouldn't self-treat at this point!