Allergies in rabbits?

My bunny is around 3 months old and has been sneezing a lot lately. He was under antibiotics when the sneezing started because he just recovered from wet tail. I assumed it was because of the bedding so I removed it and the sneezing became less but it was still present.

I consulted my vet (experienced in exotic animals and treated my previous bunnies) before showing him my new bunny. Telling him the symptoms, etc. The vet only asked me one thing: "Is he still eating?" and I said "Yes, in fact he eats a lot." I told him that the nose was moist, there were furs clumped together but no thick stuff coming out of the nostrils when he's breathing.

He further told me that it was most likely allergies because the eyes were dry and the other bunny wasn't sneezing and that it's natural for the nose to be moist (just a little). I can't really tell because the bunnies drink in a cup. I think the sneezing is getting worse. The vet recommends that I get the bunnies out for a few minutes everyday so they can breathe fresh air and soak in some sunshine and the symptom should get better.