IDK if any o this will help you but I’ll just explain my bun’s “condition” a bit.
What do you mean by sneezing? A little “choo” or a sneeze attack (several sneezes in a row)?
My rabbit has sneeze attacks, several sneezes in a row often ended by a coughing hacking noise (Luckily these sneeze attacks have lowered in frequency). She also has a frequent damp nose, but no other “symptoms”.
I took her to the vet to have a culture and trachea wash done. The culture was insufficient (as it often times is) but they ended up doing a cytology. The did find bacteria that often points to Pastuerella (“Snuffles”) (although a lot of rabbits have that bacteria in their nasal passages anyway, without being sick from it) and also signs of inflammation, caused by allergies.
I find keeping Moxie’s area VERY clean, helps her a lot. Minimizing irritants like perfumes, lotions, air fresheners, dryer sheets, ect. help. An air purifier would help as well. (allergies or not, irritants are not good for snuffles).
I would definitely phone your vet…
Good luck!