I have 6 bunnies and from time to time they will sneeze a time or two but it’s not that often. They also have no fluid or mucus that is coming out when they sneeze. It sounds like she may have an upper respiratory infection. I would take her to the vet to be on the safe side because with bunnies they don’t usually show they’re sick like other animals do. If you find a good inexpensive vet like I have it shouldn’t be to much to get her in and get antibiotics! The sooner the better!
Good luck and best wishes for you two! ?

You could try and see if it gets better with less dusty hay or another type of hay. Buns can get allergies, even to timothy. But some buns just have sensitive nasal mucosa that’s prone to mechanical irritation from particles like those in dusty hay. Commercially available hay is de-dusted, but you can get rid of more dust by pouring the hay out on a bedsheet or tarp, then collecet it back up in the bag again and dispose of the fine fragments that could cause irriation.

Switch hay brand or type. Switching brands helped Wick a lot. A lot of people talk about being allergic to dusty hay or a certain type of hay, but they don’t think about the allergy being of where the hay is grown and harvested. Wherever Kaytee brand grows their hay, Wick sneezes like crazy with it. Switching to Oxbow made wild differences. So “dusty” hay is sometimes just what’s on the hay (pollen, spores, etc.)

If it’s enough to make the fur crusty, I’d recommend going to the vet. Wick had an upper respiratory infection when I got him at 8wo and the breeder said nothing. I thought his sneezing was from a dusty environment or new environment, but it got worse rapidly very quickly.

You can trust the breeder and still take your bunny to the vet. I think a vet would be good help here in telling you if its allergies or not, and if it is, the vet might be able to help you figure out what shes allergic to.