From how you describe it, it does sound like it could be a sinus infection. Checking in with his cf dr sounds like a good idea; it sounds like he needs something to help clear it up before it has a chance to spread to his lungs. He's too young for the sinus rinses, but have you tried using the saline sprays (which can work better than the drops- the mist gets farther up there) and letting it sit in there a while and then trying to suck out whatever you can? I hope he's feeling better soon!
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<br />Emily had issues more often with ear and sinus infections as a toddler than she did with bronchial stuff.
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<br />Emily had issues more often with ear and sinus infections as a toddler than she did with bronchial stuff.