7 sneezes per hour isn’t really typical, and while rabbits w/ smooshed faces can have respiratory issues, I personally don’t attribute it to random, chronic sneezing. If the sneezing is generally always associated w/ an action, like eating hay or drinking water, then I’d be more inclined to say it’s normal external irritations. If it’s happening in the absence of anything, I would suspect something going on in the nose.

With antibiotics, you do need to commit going through it for several days and commonly multiple weeks for URIs, if you’re seeing improvement to ensure all the infectious bacteria are gone.

Considering there’s a “wet sound” (assuming outside the context of drinking sneezes?), I would discuss with your vet the pros and cons of simply trying out the antibiotic for at least a week to see if it’s worth continuing or not. There’s also no guarantee that if it is a URI, sulfatrim will be the effective antibiotic for it.

Yes, chronic sneezing doesn’t happen for no reason. There are some conditions that cause chronic sneezing, like problems with the sinuses and tooth roots. I had a bunny with this problem. But that certainly isn’t the norm. Usually, chronic sneezing is caused by a URI and antibiotics can clear that up. Most vets will simply prescribe a broad-spectrum antibiotic to see if that works. Of course, there is no guarantee that the chosen antibiotic will work against the offending bacteria. So it isn’t unheard of for a vet to simply try a different one. If that doesn’t work, then the vet may opt to try to do a culture. The reason most vets don’t jump right to a culture is because they are not always reliable. Bunnies have tons of bacteria in the sinuses. What grows may not be what is causing the symptoms.