Thanks for the info LittleLab! I didn't end up getting a vaporizer, just stuck with what the dr recommended. I originally was thinking my son's issues last week were due to the prednisone he was taking, I know it can have nasty side effects and he had never taken it before. But then his brother and dad both got sick with the same thing, so think it was just a nasty bug. He's better now, thank goodness, and has gone a streak of about 3 good days in a row, the longest in over a month. So that's a bit of good news. It only took 2 rounds of abx, prednisone, doubling his inhaler and sinus rinses to get him better.
As far as what I'm understanding from the CF doctor, this is what I think is going on (and I could be wrong, there's so much to understand with this). Because my son's numbers were not negative, there's gotta be at least one CF gene causing his numbers to be higher. But because all of my son's symptoms are considered "mild", he's thinking it could "just" be CRMS. I use that term very loosely, because the way my son's been feeling the last 3 months, I wouldn't call it "just" anything. It all started with nasal polyps, which are in both sides of his nose, but not throughout his sinuses, thankfully. And the nasacort is shrinking them down, so thankfully he's not currently in need of surgery. IF he has asthma, it's considered mild. The dr said he can't test him until he's feeling well. But because the inhaler has been helping him, the dr said this more than likely means he's got it. His lungs had what they called "mild peribronchial wall thickening". And we thought there was a growth issue so he had a bone age scan done, but it only came up a year behind, also considered "mild". He's not tiny for his age, but still small (24% height, 38% weight). But I'm only 5', and my whole family is short, so not really surprising. And he's not pancreatic insufficient, which honestly surprised me. He's been complaining of a lot of stomach aches lately, so we're assuming that's due to the sinus problems as well. When he says he's throwing up, it's just mucus, no food, so I'm not sure if he's actually "throwing up" or just gagging. He had lost about 3 pounds within a month back this fall, and he's already thin as a rail, but luckily he's put that back on.
So right now the biggest issue is his sinuses, with the next issue being his lungs. He doesn't have a chronic cough, he doesn't have allergies (we checked, twice), he's never had pneumonia, and until the last 3 months, we didn't even think he had asthma. Doctors never hear wheezing, and he's had 5 different doctors look and listen recently.