BP Occasionally Sneezes

My python is about 8-9 months old. He eats regularly, once every week, and seems to have no health issues besides sneezing. When I first got him, I was using a dirt substrate which I corrected into Aspen, which I THEN corrected into tropical forest bedding (I've forgotten the name of it, but it is large wood shavings).
After I switched his bedding I took him to see a doctor who prescribed him some antibiotics for a week just to be safe. He hasn't been sneezing since, but this week I've heard a couple huffs out of him that are worrisome to me in my lack of experience. He has shed recently, so it may also be skin stuck in his nose.
His humidity varies during the day, but he is misted regularly and usually the humidity stays between 50-80%.

Are there any fail-proof tips to stop sneezing?

The vet didn't do a culture to verify that there is no RI? As far I know, there is no way to stop sneezing because BPs shouldn't be sneezing to begin with. Assuming you have the temps and everything else good, you can try and raise the temps a few degrees overall and keep the humidity at 70-80% for a week and see if it goes away. If it doesn't, then I would suggest find a good exotic/reptile vet and get a culture done to make sure there is no RI.